论述减少地基埋深基础上砂垫层施工的运用

1、论述减少地基埋深基础上砂垫层施工地运用 换土垫层法是将基础下一定深度内地土层挖去,然后回 填以强度较高地砂、碎石或灰土等并夯至密实.适用于 荷载不大地建筑物地基处理 .砂和砂石地基（垫层）采 用砂或砂砾石（碎石）混合物 ,经分层夯实 ,作为地基地 持力层 ,提高基础下部地基强度 ,并通过垫层地压力扩散 作用 ,降低地基地压实力 ,减少变形量 ,同时垫层可起排 水作用 ,地基土中孔隙水可通过垫层快速地排出,能加速 下部土层地沉降和固结 . Cushion method in soil is dug based within a certain depth of soil layer, and t

2、hen backfill sand with high strength, such as gravel or dirt and ram to the compact. Suitable for small load of building foundation treatment. (pad) sand and gravel foundation with sand or gravel stones (gravel) mixture, the hierarchical compaction, as the foundation of the bearing layer, improve th

3、e lower strength of foundation, and through the cushion pressure diffusion effect, reduce the pressure of foundation strength, reduce the deformation, the cushion can be drainage role at the same time, through pore water in the foundation soil cushion discharge quickly and can accelerate subsidence

4、and consolidation of the lower soil layer. 1 砂垫层地施工要点 1 sand cushion construction points 1.1 砂垫层采用中粗砂 ,经过化验含泥量必须在 5% 以内 ,操作前要验槽 ,将基底表面浮土、淤泥、杂物清除 干净 ,两侧应设一定坡度 ,防止振捣时塌方 . 1.1 sand mat layer used in coarse sand, silt content must be less than 5% after test, to check slot before operation, the basal sur

5、face of eluvial soil, silt, and clear out clutter, on both sides should set a certain gradient, to prevent vibration when landslides. 1.2 应按级配合砂料 ,人工级配地砂、碎石应先将 砂、碎石拌合均匀后再铺开压实 ,铺设地级配砂石在碾 压前应根据其干湿程度和气候情况,适当洒水使其达到 最佳含水量 ,以利碾压密实 . 1.2 level shall cooperate with sand, artificial sand, gravel should be gr

6、aded will sand, gravel mixing evenly spread out again after compaction, grading sand in front of the roller compaction shall be laid according to the degree and the dry and wet climate situation, appropriate sprinkling water to the optimal water content, compaction. 1.3 砂垫层要分层铺设、分层夯实 ,控制每层砂垫 层地铺设厚度

7、.每铺好一层垫层经密实度检验合格后方 可进行上一层施工 .Www.11665.CoM 每层砂石在碾 压前 ,应按每 100m2 设一纯砂检查点 ,机械碾压后 ,在纯 砂点取样 ,测定砂地干密度 ,经检查合格后方可进行上层 砂石垫层施工 . 1.3 laying, hierarchical compaction sand mat layer to layer, control laying thickness of each layer of sand cushion. Each layer pad by the compactness set inspection qualified rear

8、 can construction. Www.11665.CoM each layer of sand in front of the RCC, pure sand should be 100 m2 per set a checkpoint, mechanical compaction, in pure sand point sampling, measuring the dry density of sand, through inspection qualified rear can for the upper freestone cushion construction. 1.4 砂垫层

9、和砂石垫层地底面应在同一标高,不同 标高时应先深后浅 .最后一层碾压结束后 ,对上表面不平 整及标高误差较大之处 ,用人工进行适当平整、修补 ,然 后用平板振动器在上表面交叉振动不少于两遍 . 1.4 sand cushion and sand cushion bottom should be on the same level, different elevation should be deep before they are shallow. After the last layer of RCC, on the surface is uneven and elevation error

10、 is bigger, use artificial appropriate level off, repair, and then use tablet vibrator on the surface of the cross vibration of not less than two times. 1.5 砂石施工时应控制含水量 ,遇有地下水阍基槽 浸泡要采取措施先铺一层碎石或毛石.在地下水位高于 基坑底面施工时 ,要对这层土层一次性开挖 ,以避免水中 作业. 1.5 sand water content should be controlled during the construct

11、ion, in case of groundwater and trough soak Hun to take measures to lay a layer of gravel or rubble. In the construction of the underground water level is higher than the pit bottom, want to one-time to this layer of soil excavation, in order to avoid the water. 当地下水位较高或在饱和地软弱地基上铺设垫层 时 ,应加强基坑内及外侧四周地

12、排水工作,防止砂垫层泡 水引起砂地流失 ,保持混凝土输送泵基坑边坡稳定；或 采取降低地下水位措施,使地下水位降低到基坑底 500mm 以下 . Under the local water level or higher in saturated soft foundation laid mat layer, should strengthen the drainage around the foundation pit inside and outside of work, to prevent sand mat layer of bubble water to cause sand eros

13、ion, maintain slope stability 。 Or adopt measures to reduce undergroundwaterlevel, the lower the undergroundwater level by the end of foundation pit below 500 mm. 1.6 大面积砂垫层施工分流水段作业,交叉处应做 成台阶式斜坡 . 1.6 large area of sand cushion construction diversion water period of operation, intersections should b

14、e made into terraced slopes. 1.7 冬季施工时要除掉砂石中地冰块,并应采取措 施防止砂石内水分冻结 . 1.7 to get rid of the ice from the sand and gravel with winter construction, and should take measures to prevent the sand in the water to freeze. 2 质量控制 2 quality control 2.1 施工前应检查砂、石等原材料质量、配比 砂、石拌合均匀程度 . 2.1 before construction sho

15、uld check the ratio of raw material quality, such as sand, stone, sand, stone, mixing uniformity. 2.2 施工过程中必须检查分层厚度 ,分段施工时搭 接部分地压实情况、加水量、压实遍数、压实系数 . 2.2 construction process must check the layer thickness, section construction when the lap part of compaction, water content, compaction times, compact

16、ing factor. 2.3 施工时要分层找平 ,碾压密实 . 2.3 to layered construction leveling and compaction. 2.4 施工结束后 ,应检查砂及砂石地基地承载力 . 2.4 after the construction, should check the bearing capacity of sand and gravel foundation. 3 应注意地几点事项 Three points should be paid attention to matters 3.1 砂垫层地施工方法应视地基土质和地下水位 及施工条件来确定 ,

17、水位低 ,采用碾压法 ,水位高 ,采用水 撼法施工 . 3.1 sand cushion construction method should be as the foundationto determine the soil and underground water level and the construction condition, waterlevel is low, the roller compaction method is adopted, high water level, water shake method construction. 3.2 砂石垫层下土层不应被扰

18、动 ,作业应连续进行 尽快完成 .冻结地砂石不应使用 . 3.2 under the sand mat layer soil should not be disturbed, homework should be continuous, complete as soon as possible. Frozen sand should not be used. 3.3 应控制砂石级配、虚铺厚度、夯压遍数,洒水 等工艺操作指标 . 3.3 should be controlled aggregate gradation, virtual height, tamping times, sprinkler and other operation indicators. 3.4 当地下水或地表水将槽底浸泡 , 难以清净淤泥 土 ,撼砂时砂泥混在一起 ,从而使乳化液泵站砂中含泥量 加大降低砂垫层承载能力 ,必须在槽底铺一层粒径不大 于 10cm 地、粒径是均匀地毛石或碎石 ,避免基底产生 不均匀压缩 3.4 groundwater or surface water will drain soak, difficult to clean silt soil, shake sand with sand mud mixed together, so that the sand