2基础回填及深基坑防护Word下载.docx

1、填土方式 分层铺填机械夯实，局部人工夯实。使用机械不同，每层铺土厚度和压实遍数也不同，见下表：填土每层的铺土厚度和压实遍数压实机具每层铺土厚度每层压实遍数（遍）平碾压路机20030068打夯机20025034人工打夯不大于150填土注意事项 （1）填土施工前，应根据工程特点，填料种类、设计压实系数、施工条件等合理选择压实机具，并确定填料含水量控制范围、铺土厚度和压实遍数等参数。所有回填土压实系数应满足设计要求。（2）夯压时，应相互搭接，防止漏压；（3）分段填土时，每层接缝处应做成斜坡形，夯压边迹重迭0.51m。上、下层错开不小于1m；（4）填方应按设计要求预留沉降量，若设计无要求时，沉降量一般

2、不超过填方高度的3%。填土压实后的质量要求 应有90%以上符合设计要求，其余10%的最低值与设计值的差，不得大于0.08g/cm3，且应分散不得集中。采用环刀取样时，基坑回填每层按100500m2 取样一组；室外回填每层按400900m2 取样一组。所有取样部位应在每层压实后的下半部。2、深基坑防护基坑开挖采用放坡开挖，但根据实际开挖时发现的地质情况和周边情况，做好边坡土钉墙支护的预案。具体施工方案如下2.1土钉墙施工锚管：采用483.0的普通钢管制作，土钉施工时应将钢管前端敲扁封闭，在钢管沿长度方向每隔0.6m旋转90度设一个8mm圆孔，圆孔从钢管端头1.0m开始设置，直至钢管前端。为提高土

3、钉的抗拔力，在钢管上每个出浆孔处焊接一块等边角钢护住孔口并作为倒刺。锚管入土方式分两种，在流塑状淤泥层及流砂层时，用普通风镐将锚管振入土层内。如土质较硬时，则先行开孔再击入。成孔对锚管、采用打入法施工。本工程主要采用锚杆钻孔机开孔，钻头直径选用100mm（成孔直径可为120140mm）。成孔后插入钢管，然后用风镐打入土中。成孔过程中，遇有障碍物需调整孔位时，不得影响支护安全。编扎钢筋网钢筋网片由焊绑而成。因编网是随开挖分层进行，故下层的竖向钢筋须用焊接接头，单面焊长不小于网筋直径的10d，横向钢筋可用绑扎接头，其搭接长度不小于200mm。钢筋网片应牢固固定在边壁上，并符合规定的保护层厚度要求。

4、注浆土钉成梅花形布置，注浆料为水泥砂浆，强度为M10。锚管（483.0）注浆注浆之前应排出管内泥水，用压力水进行洗孔，用胶管从钢管出入口处逐渐冲洗到管底，直至管内流出清水为止；最后对锚管注浆，即把注浆导管插入孔内注浆，进行加压注浆，土钉注浆开始压力不小于0.5Mpa，终了压力不小于0.3Mpa，注浆须慢速进行，注浆量按土钉长度计算确定（孔径按80算）确保注浆充盈系数不小于1.1。锚钉端部焊接3.0）端部应与加强筋、钢筋网片、及井字垫块等相互焊接。各钢筋的位置由里向外依次是：钢筋网、水平加强筋、端头井字垫块。喷射混凝土喷混凝土的喷射顺序应是自下而上，以开挖层底部向上施喷。喷头与受喷面距离控制在0

5、.81.5m范围内，射流方向垂直指向喷射面，但在钢筋部位，应先喷填钢筋和锚钉后方，然后再喷其前方，以免其后出现空隙。在继续下层喷射作业时，应仔细清除预留施工缝接合面上的浮浆层和松散碎屑，并喷水之潮湿。土钉墙面采用干喷法喷射混凝土，分两层施工，喷射第一层混凝土厚30-50mm后，打入钢管土钉，钢管内应及时注浆，然后绑扎钢筋网，最后喷射混凝土至设计厚度。面层钢筋至坑底须插入土中30cm，喷射混凝土时，可根据坑壁土层含水量和挖土速度，添加3%左右的速凝剂。喷射混凝土强度等级采用C20，一般其配合比为水泥砂碎石水=1220.45，水泥为普通硅酸盐32.5水泥，碎石的最大粒径不超过15mm，砂为中粗黄砂

6、，空压机风量不小于6m3h，喷头水压不小于0.15Mpa。2.2、支护施工要点及施工动态监测、施工要点施工前必须进行技术交底，搞清土钉排数，孔位高低、孔距、孔深及高度。测量出土钉正确位置，打入土钉，进行压力灌浆。灌浆是土钉墙施工中的一道关键工序，必须认真进行，并做好记录。待第一次喷射砼初凝后固定钢筋网及钢筋骨架，并将钢筋骨架与土钉焊接牢固，逐个检查焊接点，焊接质量必须符合要求。土钉施工时应分段分层进行。第一层每段不得超过20米。挖至淤泥层时，每段开挖不得超过8米，并采用间隔开挖；分层土方开挖时每层超挖于同层锚杆0.3-0.5m。最后一层错杆施工完应立即施工地下室垫层，并进行基坑封底。、施工动态

7、监测监测的主要内容：基坑周边、基坑顶的沉降与水平位移；基坑内外的地下水位观测；基坑土钉墙基坑深度的侧向位移及坑底以下的位移量。拟订监测计划。在基坑开挖与支护施工前，通过现场调查，拟出监测范围、项目、位置和观测点，明确观测人员、设备和时间。认真收集资料。做好原始状况的资料收集、拍照、设置观测标志，做好观测记录。一般情况下，对不同的部位按常规进行观测，但在雨后或有明显位移、沉降反映等特殊情况下，应相应增加观测次数，并做到及时观测与及时整改相结合。做好综合分析，指导下步工作。及时记录、整理观测数据。绘制位移、沉降、裂缝随时间、季节的变化曲线，综合分析基坑及周边环境的整体稳定性、安全性，根据实际情况，

8、采取相应的技术措施。2.3、土方开挖方案、准备工作组织项目部全体管理人员认真学习地质勘察资料，设计图纸及现场场地察看情况，确定最科学、经济合理的挖土方案。土方开挖前对施工现场、地下、地上障碍物进行全面调查，及时清理。根据场地情况及支护要求，确定挖土范围，根据建设单位提供的水准点及规划坐标，引测出桩位控制网络，并引测至施工机械活动范围外并做好标记。根据施工进度计划，充分利用土钉墙喷锚支护需挖土机配合的特点，利用时间、空间做到各工种、各工序的配合，保证机械施工的连续作业，确保预期完成全部土方分项的施工服务，充分体现机械化施工的高效率、高速度，针对以上特点，决定选择反铲挖土机2台，自卸载重车15辆。

9、、基坑开挖挖土机械选用2台反铲挖土机， 10辆汽车。根据土钉墙的施工，分层分段由北向南逐步退挖。挖土前要向挖土作业组作详细的技术交底。挖掘机的挖土速度应基本保持一致，不得局部一次深挖，造成卸荷过快。基坑四周应严格控制堆放荷载，不得超过15Kpa。基坑周围的地表水要及时排除，防止地表水流入基础。开挖时，下层土或相邻段土的开挖须分别待上层或相邻段土钉施工完毕24小时后方可进行。土方开挖须与土钉墙施工全过程密切配合。机械挖土挖至设计板底下300mm处时，以下部分由人工挖土，若承台低于基础底板，由人工进行挖槽，运土至挖土机工作范围，抓出运出。在基坑挖土时要及时观察周边环境变化，加强周边环境的观察，及时

10、反馈信息，根据观察结果进行计算，对发生异常情况及时处理。Second, backfill foundation and deep foundation pit protection 1, backfill foundation earthwork The earthwork backfilling sinotrans earthwork backfilling, 3 km distance to the left. Basis of backfill soil and the proportion of backfilling there. filling order Indoor and o

11、utdoor symmetric backfilling, prevent the lateral pressure of backfill soil lateral basis. The filling soil should comply with the design requirements. If no request design, shall comply with the following provisions:（1） Of gravel soil, sandy soil, can be used as the surface of the packing;（2） Water

12、 content conform to the requirements of the cohesive soil compaction, can be used for each layer of packing;（3） The fragments grass and more than 8% of soil organic matter content, not only for the compaction requirements of the fill;（4） Packing contains salt crystal, salt pieces or salt plants cann

13、ot be used as the foundation of backfill soil;（5） Packing in each layer of maximum diameter shall not be more than two-thirds of the fill thickness shop, the shop when fill material should not focus on large. Filling way Layered fill mechanical shop ramming, local artificial ramming ,Use machinery i

14、s different, every layer thickness and spread soil compaction is different also, see table:Each of the filled soil layer thickness and spread soil compaction Compaction machine Each layer thickness soil spread Each layer compaction Flat grinding roller ramming machineArtificial rammingNot more than

15、150 The filling the matters needing attention （1） Filling before construction, should according to the features of the project, packing kinds, design compaction coefficient, construction condition and reasonable choice compaction machine, and determined the packing water content, the control range t

16、hickness and soil compaction parameters. All backfill soil compaction coefficient should meet the design requirements. （2） Ramming pressure, should be mutually lap, prevent leakage pressure;（3） Section of the filled soil, each layer juncture place should press edge tracing overlapping 0.5 1 m. On th

17、e lower stagger, not less than 1 m;（4） Fill should press the design requirements to reserve the settlement, if design without the requirement, the settlement in general not more than fill the height of the 3%. （5） After the filled soil compaction quality requirements Should comply with the design re

18、quirements of more than 90%, and the remaining 10% of the lowest of the poor and the design value, and shall not be more than 0.08 g/cm3, and should not focus on scattered. The sampling, each layer of backfill foundation pit in 100 500 m2 sampling a group; Outdoor backfilling every layer of 400 900

19、m2 sampling in a group. All sampling in each layer part should be compacted lower half. 2, Deep foundation pit protection The foundation pit excavation put slope excavation, but according to actual excavation discovered when geological condition and surrounding situation, completes the slope soil na

20、iling wall of the plan. Specific construction scheme as follows:2.1 the soil nailed wall construction Anchor tube: the 48 x 3.0 ordinary steel tube is made, soil nail when construction should be closed flat steel pipe on the front, in steel along the length direction every 0.6 m rotating 90 degrees

21、set a 8 mm round hole, round hole from steel tube end 1.0 m begins to set until the steel pipe front end. In order to improve the resistance of the soil nailing pull force, in the steel pipe on the pulp out each hole in a steel welding equilateral covered orifice and as a thorn. The way to come back

22、 as the anchor of two, in plastic flow of silt layer and flow of sand layer, use common pneumatic picks will anchor within the soil. Such as soil harder, the first hole and into the again . Into hole. Anchored by tube, construction method into. The project mainly USES the bolt hole drilling machine,

23、 choose 100 mm diameter drill （into hole diameter can be for 120 140 mm）. After the steel tube inserted into a hole, and then into the soil with pneumatic picks. Into holes in the process, if the obstacles need to adjust a hole, shall not affect the safety support. Make up firm steel By welding of s

24、teel tie . Make up nets is because with the excavation layered, so the vertical steel welding joint must use, one-sided welding long not less than the diameter of the 10 d steel nets, steel locally available transverse joint, the lap length not less than 200 mm. Steel mesh piece shall be firmly on t

25、he walls, and in conformity with the provisions cover thickness requirements. Grouting Soil nail into the plum flower form to decorate, note slurry for cement mortar. Anchor tube （phi 48 x 3.0） grouting Before discharge tube should be the grouting, with pressure water wash hole, with hose from the e

26、ntrance to a steel pipe flushing to the bottom of the tube gradually, until the outflow water pipe so far; The last to anchor the grouting, that of grouting catheter inserted hole grouting, the pressure grouting, soil nail grouting began to pressure is not less than 0.5 Mpa, pressure is not the end

27、of less than 0.3 Mpa, grouting must be slower speed, grouting quantity of soil nailing according to calculate and determine the length （aperture by 80 calculate） ensure that filled with grouting coefficient is not less than 1.1. Anchor was at the end of the welding Anchor tube （phi 48 x 3.0） should

28、be reinforced and at the end of the piece, reinforcement fabric, and the well character pad is mutual welding etc. The position of the reinforced by outward in order: steel mesh, horizontal reinforcing well character spacers. Sprayed concrete Spray the order should be sprayed concrete bottom-up, exc

29、avation layer to the bottom was up sprays. The shower nozzle and the spray surface distance control in 0.8 1.5 m range, vertical direction to spray surface jet, but in reinforced part, should first fill in steel and anchor spray nail rear, then spray the front, lest appear after the gap. The homewor

30、k in continue to spray, carefully remove reserve construction seam on bonding floating cement layer and the loose debris, and the wet water. Soil nail metope USES dry spray method jet concrete, two layer construction, spray the first layer of concrete thick 30 to 50 mm, soil nail into the steel pipe

31、, steel pipe shall timely grouting, then binding reinforcement fabric, finally sprayed concrete thickness to design. The surface must be reinforced to insert the soil in the den 30 cm, jet concrete based on soil moisture content and digging pit wall speed, add 3% of accelerating. Jet concrete strength level using C20, general the ceme