砂土地层污水干管顶管施工处治数值分析

Numerical study on pipe jacking construction treatment of sewer in sand stratum

为研究在砂土地层中顶管施工注浆处治的加固效果,以西安某污水干管顶管施工注浆处治为对象,通过现场调查、GPR探测,确定管顶上方存在的空洞和松散范围,利用弹塑性有限元模型,对注浆处治前后管道周围土体的位移及应力变化规律以及不同注浆压力下的注浆效果进行研究。结果表明:(1)与无注浆加固工况相比,注浆处治能明显改善土体的竖向位移、横向位移和应力不均现象,并且经过注浆加固处理后,管道周围的塑性应变区明显变小;(2)通过比较0.25、0.3 MPa注浆压力下位移和应力变化规律发现,0.25MPa的注浆压力足以达到实际需要的处治效果;(3)注浆作用下,距管道外径3D(D为管道外径)范围内土体的横向变形较明显,距管道外围2D范围内土体竖向应力变化较明显,土体横向应力变化明显的区域为横向约为4D,竖向约为2D。

Based on the pipe jacking construction treatment of a sewer in Xi＇an,the range of loose area and the location of voids above the tunnel were determined by field investigation and ground penetrating radar（GPR）exploration.The displacement and stress of soil around the pipe during grouting were studied by using the elastic-plastic finite element model,meanwhile,the grouting effect under the different grouting pressure was also studied.The results are as follows：Firstly,the soil vertical displacement,transverse deformation and unevenly distributed stress can be significantly improved by grouting treatment,and the plastic strain range around the pipe decreases significantly after grouting.Besides,the grouting pressure of0.25 MPa is sufficient to meet the actual need of the treatment compared with the grouting pressure of 0.3 MPa by the comparison of the mechanisms of displacement and stress.Moreover,the transverse deformation of soil in the range of 3D（D,the pipe outer diameter）is obvious,with the soil vertical stress changing obviously in the range of 2D,and the range is about 4Din horizontal and 2Din vertical,in which the transverse stress of soil changes significantly.