复杂地层超深地连墙接缝止水加固技术与控制

Technology and Control of Water Sealing and Reinforcement of Ultra-deep Underground Diaphragm Wall Joints in Complex Strata

摘要:

针对承压水复杂地层地下连续墙易发生接缝渗漏问题,采用RJP、MJS及N-Jet工法桩等方式对地下连续墙接缝进行止水加固以控制基坑渗漏。以上海某轨道交通工程为依托,通过75m超深RJP、MJS及N-Jet工法桩试验,分析超深地下连续墙接缝止水加固技术与成桩效果,并提出相应控制措施。现场试桩试验结果表明：(1)引孔质量直接影响成桩效果,可以通过钢套筒护孔、测斜纠偏等措施提高引孔质量；(2)成桩深度在45m以内土层以粘性土为主地层,成桩效果较好,取芯试件的强度和抗渗能满足要求；(3)成桩深度大于45m、以⑦2密实性粉砂为主地层,RJP、MJS、N-Jet工法成桩取芯效果不能满足要求；(4)采用RJP、MJS及N-Jet工法桩对超深地连墙墙缝位置进行止水效果强化时,应关注土层性质随深度变化情况,适时调整施工控制参数。

Abstract:

Aiming at the problem of joint leakage of underground diaphragm wall in complex strata of confined water, the piles of RJP, MJS and N-Jet methods are used to seal and reinforce the joints of underground diaphragm wall in order to control the leakage of foundation pit. Based on a rail transit project in Shanghai, through 75 m ultra-deep pile tests of RJP, MJS and N-Jet methods, the water-sealing reinforcement technology of ultra-deep underground diaphragm wall joints and the pile-forming effect are analyzed, and the corresponding control measures are proposed. The field pile test results show that the quality of the pilot hole directly affects the pile forming effect. The quality of the pilot hole can be improved by the measures such as steel sleeve hole protection and survey deviation correction. When the pile-forming depth is less than 45 m and the soil layer is mainly composed of cohesive soil. The pile-forming effect will be good. The strength and impermeability of the coring specimen meet the requirements. The pile-forming coring effects of RJP, MJS and N-Jet methods cannot meet the requirements when the pile-forming depth is greater than 45 m and the main stratum is composed of ⑦2 dense silt. When the piles of RJP, MJS and N-Jet methods are used to strengthen the water-sealing effect at the joint position of ultra-deep underground diaphragm wall, the attention should be paid to the property of the soil layer with the depth variation. The construction control parameters should be adjusted timely.