新奥法英文文献翻译

NATM tunnel design principle in the construction of major and

Construction Technology

I.The NATM Design Principle

1.Tunnel design and construction of two major theoretical and development process Since the 20th century, human space on the ground floor of the growing demand, thus the underground works of the study of a rapid development. In a large number of underground engineering practice, it is generally recognized that the tunnel and

underground cavern project, the core of the problem, all up in the excavation and retaining two key processes. How excavation, it will be more conducive to the stability and cavern facilitate support : For more support, supporting how they can more effectively ensure stability and facilitate the cavern excavation. This is the tunnels and underground works two promote each other and check each other's problems.

Tunnels and underground caverns, and focusing on the core issues with the above practice and research, in different periods, People of different theories and gradually established a system of different theories, Each system includes theory and resolve (or are studying the resolution) from the works of understanding (concept), mechanics, engineering measures to the construction methods (Technology), a series of engineering problems.

A theory of the 20th century the 1920s the traditional \content is : a stable rock self-stability, no load : unstable rock may have collapsed. need shoring structure to be supported. Thus, the role of the supporting structure of the rock load is within a certain range may be due to relaxation and collapse of rock gravity. This is a traditional theory, and their representative is Taishaji and Principe's and others. It works similar to the surface issues of the thinking is still widely used to.

Another theory of the 20th century made the 1950s the modern theory of timbering or \self-stability : unstable rock loss of stability is a process, and if this process in providing the necessary help or restrictions will still be able to enter the rock steady state. This theoretical system of representative characters Labuxiweici, Miller-Feiqieer, Fenner - Daluobo and Kashitenai others. This is a more modern theory, it is already out of the ground works to consider the ideas, and underground works closer to reality, the past 50

years has been widely accepted and applied. demonstrated broad development prospects.

Can be seen from the above, the former theory more attention to the findings and the results of treatment : The latter theory is even more attention to the process and the control of the process, right from the rock for the full utilization of capacity. Given this distinction, which both theory and methods in the process, each with different performance characteristics. NATM theory is rock for the tunnel engineering practice in the representation method.

2. NATM

NATM that the new Austrian Tunneling Method short the original is in New Austrian Tunneling Method, referred to as the NATM. France said it convergence bound or some countries alleged to observe the dynamic design and construction of the basic principles.

NATM concept of filibustering Xiweici Austria scholars in the 20th century, Professor age of 50. It was based on the experience of both the tunnel and rock mechanics theory, will bolt and shotcrete combination as a major means of supporting a construction method, Austria, Sweden, Italy and other countries, many practical and theoretical study in the 1960s and patented officially named. Following this approach in Western Europe, Scandinavia, the United States and Japan and many other underground works with a very rapid development, have become modern tunnels new technologies landmark. Nearly 40 years ago, the railway sector through research, design, construction combining, in many construction of the tunnel, according to their own characteristics successfully applied a new Austrian law, made more experience, have accumulated large amounts of data, This is the application stage. However, in the road sector NATM of only 50%. Currently, the New Austrian Tunneling Method almost become weak and broken rock section of a tunnel construction method, technical and economic benefits are clear. NATM the basic points can be summarized as follows :

（1）. Rock tunnel structure is the main loading unit, the construction must fully protect the rock, it minimize the disturbance to avoid excessive damage to the intensity of rock. To this end, the construction of sub-section should not block too much, excavation should be used smooth blasting, presplit blasting or mechanical tunneling.

（2）. In order to give full play to rock the carrying capacity should be allowed to control and rock deformation. While allowing deformation, which can be a rock bearing ring; The other hand, have to limit it, Rock is not so lax and excessive loss or greatly reduced carrying capacity. During construction should be used with rock close

to, the timely building puzzle keeps strengthening Flexible support structure, such as bolting and shotcreting supporting. This adjustment will be adopted supporting structural strength, Stiffness and its participation in the work of the time (including the closure of time) to control the deformation of the rock mass.

（3）. In order to improve the support structure, the mechanical properties, the construction should be closed as soon as possible, and to become a closed cylindrical structure. In addition, the tunnel shape with a round should, as far as possible, to avoid the corner of the stress concentration.

（4）. Construction right through the rock and supporting the dynamic observation, measurement, and reasonable arrangements for the construction procedures, changes in the design and construction management of the day-to-day.

（5）. To lay waterproof layer, or is subject to bolt corrosion, deterioration of rock properties, rheological, swelling caused by the follow-up to load, use composite lining.

（6）. Lining in principle, and the early rock deformation Supporting the basic stability of the conditions under construction. rock and supporting structure into a whole, thereby improving the support system of security.

NATM above the basic elements can be briefly summarized as : \early spray anchor, ground measurements, closed tight.\

3．With a spring to understand the principle NATM

（1）. Cavern brink of a point A in the original excavation ago with stress (stress self-respect and tectonic stress) in a state of equilibrium. As an elastic stiffness of the spring K, P0 under compression in a state of equilibrium.

（2）. Cavern excavation, A point in attacking lose face constraints, the original stress state to be adjusted, if the intensity of rock big enough, After less stress adjustments may cavern in a stable condition (without support). But most of the geological conditions of the poor, that is, after the stress cavern adjustments, such as weak protection, we could have convergence deformation, even instability (landslides), must be provided to support power PE, in order to prevent landslides instability. Equivalent to the Spring of deformation u, in the role of PE is now in the midst of a state of equilibrium.

（3）. By the mechanical balance equation, we can see in the spring P0 role in a state of equilibrium; Spring in the event of deformation u, PE in the role they will be in equilibrium, assuming spring elasticity of K, were : P0=PE+Ku

Discussion :

（1）. When u = 0, that is not allowed P0=PE rock deformation, is a rigid support, not economic;

（2）. When u ↑, PE ↓; When u ↓, PE ↑. That is, rock deformation occurred, the release of some of the load (unloading), we should allow some extent rock deformation, to give full play to rock the capacity for self. Is an economic support measures, the rock self-stability P=P0-PE=Ku;

（3）. When u=umax, landslides, have relaxation load and unsafe. 4. Points

（1）. Rock cavern excavation is affected by that part of rock (soil) body, the rock is a trinity : have a load bearing structure, building materials.

（2）. Tunnel construction is in the rock stress is of special architectural environment, which can not be equated with the construction on the ground.

（3）. Tunnel structure rock + = bracing system. II. The main tunnel construction technology

1. Cave construction :

（1）.excavation slope around :

Lofting total station measurements, the use of excavators from top to bottom, paragraph by paragraph excavation, not the amount of excavation or the end of next overlapping excavation, remove pits with the above may slump topsoil, shrubs and rock slopes, rock strata of slope excavation needs blasting, Discussion should focus mainly loose blasting. Also partial artificial finishing, when excavation and inspection slope of slope, if sliding and cracking phenomenon and slowing down due slope.

（2）.Cheng Tung-supporting :

Yang Brush Singapore Singapore after the completion of timely inspection plate slope gradient, the gradient to pass the inspection, the system set up to fight time anchor, and the exposed bolt heads, hanging metal based network expansion and bolt welding into first overall. Linked network immediately after the completion of shotcrete and repeatedly jet until it reaches the thickness of the design so far. （3）.as of gutter construction :

Yang slope away from the groove 5 meters excavation ditch interception, interception gutter mainly mechanical excavation, artificial finishing, after dressing, 7.5# immediately masonry made of mortar and stones, and the floor surface with mortar.

2. Auxiliary construction : （1）A long pipe roof :

Sets arch construction : construction Lofting, template installation, assembling reinforcement, the guidance of lofting 127 installation guide, concrete pouring.

Pipe specifications : Heat Nazarbayev Seamless Steel Tube ￠ 108 mm and a thickness of 6 mm, length of 3 m, 6 m; N pipe from : Central to the distance 50 cm;

N Inclination : Elevation 1 ° (the actual construction works by 2 °), the direction parallel with the Central Line;

N pipe construction error : Radial not more than 20 cm;

N tunnel longitudinal joints within the same section with more than 50% adjacent pipe joints staggered at least a meter. A. pipe roof construction method :

Lofting accurate measurement personnel, marking the centerline and the vault out of its hole elevation, soil excavation reserved as a core pipe roof construction work platform Excavation footage of 2.5 meters, after the end of excavation, artificia symmetrical on both sides of excavation (Commodities H) platform, level width of 1.5 meters, 2.0 meters high, as construction sets and pipe arch shed facilities drilling platform. Pipe-roof design position should be and it should be a good hole steel tube, grouting after playing non-porous tube steel, non-porous tube can be used as pipe inspection, Grouting quality inspection, drill vertical direction must be accurately controlled to guarantee the opening hole to the right, End each drilling a hole is a pipe jacking, drilling should always use dipcompass drilling pipe measuring the deflection, found that the deflection over design requirements in a timely fashion. Pipe joints using screw connection, screw length 15 cm, to stagger the pipe joints, odd-numbered as the first section of the introduction of three-meter steel pipes and even numbered the first section of pipe using 6 meters, After each have adopted six-meter-long steel pipe.

B. pipe roof construction machinery :

N drilling machinery : XY-28-300 equipped with electric drill, drilling and pipe jacking long shelf;

N grouting machine : BW-250/50-injection pump two Taiwan;

N using cement-water glass slurry. Mud and water volume ratio 1:0.5; water glass slurry concentration of water-cement ratio 1:1 silicate 35 Baume; The efficacy silicate modulus pressure grouting pressure early pressure 2.0MPA 0.5~1.0MPA; end.

（2）. a small catheter

A. small catheter used ahead diameter of 42 mm and a thickness of 3.5 mm thermal Nazarbayev seamless steel tubes, steel pipe was front-tip, Welding on the tail ￠ 6 stiffening brace and the wall around the drilling hole grouting 8 mm, but the tail of a meter without grouting holes and Advance Construction of a small catheter, the tubes and the lining of the centerline parallel to 10 ° -30 ° Chalu into the rock arch. penstocks to 20-50 cm spacing. Each was over a steel tubes, should be closed immediately shotcrete

excavation face and then grouting. After grouting, erecting steel Arch, Supporting the early completion of every (2-3 meters, and the paper attempts to be) another one for steel tubes, Advance small catheter general lap length of 1.0 meters.

B. Grouting parameters :

N water slurry and water glass volume : 1:0.5; N slurry water-cement ratio 1:1

N 35 Baume concentration of sodium silicate; The efficacy silicate modulus N grouting pressure 0.5~1.0MPA; if necessary, set up only orifice Pulp Cypriots. （3）. bolting ahead : The Chalu must be greater than 14 degrees, grouting satiated and lap length is not less than 1 meter.

3.Correcting construction :

Embedded parts used by the Design Dimensions plank make shape design, installation in contrast snoop plate car, and position accuracy (error ± 50CM), the firm shall not be fixed, you must be in possession of the wire through the middle wear.

4. Leveling Construction

Installation templates, at the request of both sides leveling layer calibration position to install template. Side-channel steel templates used [10#, top elevation with a corresponding length of the road elevation unanimously to allow deviation ± 2mm. adjusted using the

standard measurement to determine elevation. Every template fixed a certain distance from the outside to ensure that no displacement, the joints template close comfort, not from a slit, crooked and formation, and the bottom connector templates are not allowed to leak plasma. Concrete before reperfusion, the bottom surface of concrete must be clean. When the concrete arrived at the construction site directly installed backward mode of the road bed, and using artificial Huabu uniform. Concrete paver should be considered after the earthquake destroyed the settlement. Unrealistically high can be 10% higher, Lan is the surface elevation and design line. Concrete earthquake destroyed at or anywhere near the corner with plug-Lan Lan pound for pound order; Flat-Lan pound for pound crisscross comprehensive Lan, Inside each location is no longer the time for concrete sinks, no longer emitted large bubbles, and the surface of cement mortar later. normally no less than 15 seconds, also should not be too long; Then Chun-pound beam along the longitudinal Lan-pound trailer, With redundant Chun-pound concrete beams were dragged shift Trim, Dixian Department should keep leveling Lan facts. Finally, the diameter 75~100mm rolling seamless steel pipe for further leveling. Just do prohibited in the surface spraying water, and threw cement.

5. Water, cable duct construction

Install groove wall reinforcement of location accuracy, the line must be linked to the construction. Install groove wall purity, the purity requirements of accurate location, a vertical line. Dyadic greatest degree of not more than 3 mm, and template-Ditch The top-pronged, pass the inspection before the concrete reperfusion, on the side of the original wall must pick hair, and embedded parts to the location accurately. Template using stereotypes purity.

6.Gate Construction

Cleared the site for construction layout. By design size requirement dug-wall basis. M7.5# masonry made of mortar and stones.

Template installation, location accuracy requirements purity, a vertical line, and timely inspection template slope. Concrete pouring 15 # Riprap concrete, concrete strength to be more than 70% for Myeongdong vault backfill.

Myungdong vault backfill should hierarchical compaction said. The typical thickness of less than 0.3M, both backfill surface height difference of not more than 0.5M. restored

to the vault after the pack to design hierarchical compaction high, the use of machines rolling, Ramming must manually filled to vault over 1.0M before mechanical compaction .

新奥法设计原理在隧道施工中的应用及主要施工工艺

Ⅰ、新奥法的设计原理

一、隧道设计施工的两大理论及其发展过程

二十世纪以来，人类对地下空间的需求越来越多，因而对地下工程的研究有了一个突飞猛进的发展。在大量的地下工程实践中，人们普遍认识到，隧道及地下洞室工程，其核心问题，都归结在开挖和支护两个关键工序上。即如何开挖，才能更有利于洞室的稳定和便于支护：若需支护时，又如何支护才能更有效地保证洞室稳定和便于开挖。这是隧道及地下工程中两个相互促进又相互制约的问题。

在隧道及地下洞室工程中，围绕着以上核心问题的实践和研究，在不同的时期，人们提出了不同的理论并逐步建立了不同的理论体系，每一种理论体系都包含和解决（或正在研究解决）了从工程认识（概念）、力学原理，工程措施到施工方法（工艺）等一系列工程问题。

一种理论是二十世纪20年代提出的传统的“松弛荷载理论”。其核心内容是：稳定的岩体有自稳能力，不产生荷载：不稳定的岩体则可能产生坍塌，需要用支护结构予以支撑。这样，作用在支护结构上的荷载就是围岩在一定范围内由于松弛并可能塌落的岩体重力。这是一种传统的理论，其代表人物有泰沙基和普氏等人。它类似于地面工程考虑问题的思想，至今仍被广泛的应用着。

另一种理论是二十世纪50年代提出的现代支护理论，或称“岩承理论”。其核心内容是：围岩稳定显然是岩体自身有承载自稳能力：不稳定围岩丧失稳定是有一个过程的，如果在这个过程中提供必要的帮助或限制，则围岩仍然能够进入稳定状态。这种理论体系的代表性人物有拉布西维兹、米勒-菲切尔、芬纳-塔罗勃和卡斯特奈等人。这是一种比较现代的理论，它已经脱离了地面工程考虑问题的思路，而更接近于地下工程实际，近半个世纪以来已被广泛接受和推广应用，并且表现出了广阔的发展前景。

由以上可以看出，前一种理论更注意结果和对结果的处理：而后一种理论则更注意过程和对过程的控制，即对围岩自承能力的充分利用。由于有此区别，因而两种理论体系在过程和方法上各自表现出不同的特点。新奥法是岩承理论在隧道工程实践中的代表方法。

二、新奥法

新奥法即新奥地利隧道施工方法的简称，原文是New Austrian Tunnel- ling Method,简称为NATM。它与法国称收敛约束法或有些国家所称动态观测设计施工法的基本原则一致。

新奥法概念是奥地利学者拉布西维兹教授于二十世纪50年代提出的。它是以既有隧道工程经验和岩体力学的理论为基础，将锚杆和喷射混凝土组合在一起作为主要支护手段的一种施工方法，经奥地利、瑞典、意大利等国的许多实践和理论研究，于60年代取得专利权并正式命名。之后这个方法在西欧、北欧、美国和日本等许多地下工程中获得极为迅速的发展，已成为现代隧道工程新技术的标志之一。我国近40年来，铁路等部门通过科研、设计、施工三结合，在许多隧道修建中，根据自己的特点成功地应用了新奥法，取得了较多的经验，积累了大量的数据，现已进入推广应用阶段。但在公路部门新奥法的应用仅为50%左右。目前新奥法几乎成为在软弱破碎围岩地段修建隧道的一种基本方法，技术经济效益是明显的。新奥法的基本要点可归纳如下：

1.岩体是隧道结构体系中的主要承载单元，在施工中必须充分保护岩体，尽量减少对它的扰动，避免过度破坏岩体的强度。为此，施工中断面分块不宜过多，开挖应当采用光面爆破、预裂爆破或机械掘进。

2.为了充分发挥岩体的承载能力，应允许并控制岩体的变形。一方面允许变形，使围岩中能形成承载环；另一方面又必须限制它，使岩体不致过度松弛而丧失或大大降低承载能力。在施工中应采用能与围岩密贴、及时筑砌又能随时加强的柔性支护结构，例如，锚喷支护等。这样，就能通过调整支护结构的强度、刚度和它参加工作的时间（包括闭合时间）来控制岩体的变形。

3.为了改善支护结构的受力性能，施工中应尽快闭合，而成为封闭的筒形结构。另外，隧道断面形状应尽可能圆顺，以避免拐角处的应力集中。

4.通过施工中对围岩和支护的动态观察、量测，合理安排施工程序、进行设计变更及日常的施工管理。

5.为了敷设防水层，或为了承受由于锚杆锈蚀，围岩性质恶化、流变、膨胀所引起的后续荷载，可采用复合式衬砌。

6.二次衬砌原则上是在围岩与初期支护变形基本稳定的条件下修筑的，围岩和支护结构形成一个整体，因而提高了支护体系的安全度。

上述新奥法的基本要点可扼要的概括为：“少扰动、早喷锚，勤量测、紧封闭”。 三、用一个弹簧来理解新奥法原理

1.洞室边缘某一点A在开挖前具有原始应力（自重应力和构造应力）处于一个平衡状态。如同一根弹性刚度为K的弹簧，在P0作用下处于压缩平衡状态。

2.洞室开挖后，A点在临空面失去约束，原始应力状态要调整，如果围岩的强度足够大，那么经过应力调整，洞室可处于稳定状态（不需支护）。然而大多数的地质情况是较差的，即洞室经过应力调整后，如不支护，就会产生收敛变形，甚至失稳（塌方），所以必须提供支护力PE，才能防止塌方失稳。等同于弹簧产生了变形u后，在PE作用又处于平衡状态。

3.由力学平衡方程可知，弹簧在P0作用时处于平衡状态；弹簧在发生变形u后，在PE的作用下又处于平衡状态，假设弹簧的弹性系数为K，则有：P0=PE+Ku

讨论：

（1）当u=0时，P0=PE 即不允许围岩变形，采用刚性支护，不经济； （2）当u↑时，PE↓；当u↓时，PE↑。即围岩发生变形，可释放一定的荷载（卸荷作用），所以要允许围岩产生一定的变形，以充分发挥围岩的自承能力。是一种经济的支护措施，围岩的自稳能力P=P0-PE=Ku；

（3）当u=umax时，发生塌方，产生松驰荷载，不安全。 四、要点

1.围岩是受洞室开挖影响的那一部分岩（土）体，围岩是三位一体的即：产生荷载、承载结构、建筑材料。

2.隧道是修筑在应力岩体中的，具有特殊的建筑环境，不能等同于地面建筑。 3.隧道结构体系=围岩+支护体系。 Ⅱ、隧道主要施工工艺 一、 洞口段施工： 1.边仰坡开挖：

全站仪测量放样，利用挖掘机自上而下逐段开挖，不得掏底开挖或上下重叠开挖，清除洞口与上方有可能滑塌的表土，灌木及山坡危石等，石质地层仰坡开挖需要爆破

时，应以浅眼松动爆破为主。局部也可人工配合修整，开挖时应随时检查边坡和仰坡，如有滑动、开裂等现象，应适当放缓坡度。 2.成洞面支护：

仰坡刷坡完成后，及时用坡度板检查坡度，待坡度检查合格后，及时打设系统锚杆，并将锚杆头外露，挂设金属扩张网与锚杆头焊接成整体。挂网完成后立即喷射混凝土，并反复喷射，直到达到设计厚度为止。

3.截水沟施工：

在距仰坡坡口5米处开挖截水沟，截水沟开挖以机械为主，人工配合修整，修整完后，立即砌筑7.5#浆砌片石，并用砂浆抹面。

二、辅助施工： 1.长管棚：

套拱施工：施工放样，模板安装、钢筋绑扎、导向管放样，127导向管安装，砼浇注。

钢管规格：热扎无缝钢管￠108mm，壁厚6mm，节长3m，6m； n 管距：环向间距50cm；

n 倾角：仰角1°（实际施工按2°施工），方向与线路中线平行； n 钢管施工误差：径向不大于20㎝；

n 隧道纵向同一截面内接头数不大于50%，相邻钢管的接头至少错开1m。 A 管棚施工方法：

测量人员准确放样，标出洞中心线及拱顶标高，开挖预留核心土作为管棚施工的工作平台，开挖进尺为2.5m，开挖结束后，人工两边对称开挖（品字型）工作平台，台阶宽度1.5m，高度2.0m，作为施工套拱和管棚施钻的平台。管棚应按设计位置施工，应先打有孔钢花管，注浆后在打无孔钢花管，无孔管可作为检查管，检查注浆质量，钻机立轴方向必须准确控制，以保证孔口的孔向正确，每钻完一孔便顶进一根钢管，钻进中应经常采用测斜仪量测钢管钻进的偏斜度，发现偏斜超过设计要求，及时纠正。钢管接头采用丝扣连接，丝扣长15cm，为使钢管接头错开，编号为奇数的第一节管采用3m钢管，编号为偶数的第一节管采用6m钢管，以后每节均采用6m长钢管.

B 管棚施工机械：

n 钻孔机械：配备XY-28-300电动钻机，钻进并顶进长管棚； n 注浆机械：BW-250/50型注浆泵2台；

n 采用水泥-水玻璃浆液。水泥浆与水玻璃体积比1：0.5；水泥浆水灰比1：1；水玻璃浓度35波美度；水玻璃模数2.4；注浆压力初压0.5~1.0MPA；终压2.0MPA。

2.小导管

A. 超前小导管采用外径42mm、壁厚3.5mm的热扎无缝钢管，钢管前端呈尖锥状，尾部焊上￠6加劲箍，管壁四周钻8mm压浆孔，但尾部有1m不设压浆孔，超前小导管施工时，钢管与衬砌中心线平行以10°~30°外插角打入拱部围岩，钢管环向间距20~50㎝。每打完一排钢管后，应立即喷浆封闭开挖面,然后注浆.注浆后，架设钢拱架，初期支护完成后，每隔（2~3m，试图纸而定）再另打一排钢管，超前小导管搭接长度一般为1.0m。

B. 注浆参数：

n 水泥浆与水玻璃体积比：1：0.5； n 水泥浆水灰比1：1；

n 水玻璃浓度35波美度；水玻璃模数2.4；

n 注浆压力0.5~1.0MPA；必要时在孔口设置止浆塞。

3、超前锚杆：外插角必须大于14°，注浆饱满，搭接长度不小于1m。 三、 预埋件施工：

预埋件按设计尺寸采用木版作成设计形状，安装于二衬魔板台车中，且位置准确（误差±50cm），固定牢固不得晃动，有管的必须中间穿铁丝通过。

四、调平层施工

模板安装的要求，在调平层两侧预先标定的位置上安装模板。侧模采用[10#槽钢模板，顶面标高应与相应里程的路面标高一致，允许偏差±2mm，用水准测量调整、确定标高。模板每隔一定距离内外固定，保证不位移，模板的接头应紧密平顺，不得有离缝、歪斜和不平整等现象，模板接头及底部均不得漏浆。砼灌注前，底层砼面上必须清洗干净。当砼运达施工地点时，直接倒向安装好模的路槽内，并用人工找补均匀。摊铺时应考虑砼震捣后的沉降量。虚高可高出10%，使震实后的面层标高与设计相符。砼震捣时靠近边角等处用插入式震捣器顺序震捣；用平板式震捣器纵横交错全面震捣，每个位置的捣时间以砼不再下沉，不再冒出大量气泡，并以在表面出现水泥砂浆为准，一般不少于15s，亦不宜过长；然后用震捣梁沿纵向震捣拖平，多余的砼随着震捣梁的拖移被刮去，低陷处则应随时找平震实；最后用直径75~100mm的无缝钢管滚压，作进一步整平。严禁在刚做好的面层上洒水、撒水泥。

五、水、电缆沟施工

安设沟墙钢筋，要求位置准确，必须挂线施工。安设沟墙摸板，要求摸板位置准确，纵向一条线。最大矢度不大于3mm，模板面与沟墙顶面齐，经检查合格后方可灌注砼，在靠原边墙侧部分必须凿毛，并注意预埋件的位置准确。模板采用定型摸板。

六、洞门施工

清理现场，进行施工放样。按设计尺寸要求挖端墙基础。砌筑M7.5#浆砌片石。 模板安装，要求摸板位置准确，纵向一条线，并及时检查模板坡度。浇注砼15#

片石砼，待砼强度达到70%以上进行明洞拱顶回填。

明洞拱顶回填应对称分层夯实。每层厚度不大于0.3M，其两侧回填面高差不大于0.5M，回填至拱顶平齐后分层压实至设计高度，使用机械碾压时，必须用人工夯填至拱顶1.0M以上，方可采用机械夯实。

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