主动区溶洞对桩锚支护基坑稳定性的影响  

The Influence of Karst Cave in Active Zone on Stability of Pile-Anchor Supporting Foundation Pit

作　　者：李金奎[1,2] 高家宁 LI Jin-kui;GAO Jia-ning(College of Civil Engineering and Architecture,Dalian University,Dalian 116622,China;Dalian Tunnel and Underground Engineering Center,Dalian 116622,China)

机构地区：[1]大连大学建筑工程学院,大连116622 [2]大连市隧道与地下工程中心,大连116622

出　　处：《科学技术与工程》2021年第13期5491-5498,共8页Science Technology and Engineering

基　　金：国家自然科学基金(51174038,51878108);辽宁省教育厅项目(L2014693)。

摘　　要：为了研究存在最危险滑移面时主动区溶洞对桩锚支护基坑稳定性的影响,首先运用FLAC3D软件模拟出没有溶洞时基坑最危险滑移面的位置,然后再分别模拟出主动区不同位置、不同大小的溶洞对桩体最大水平位移和弯矩、锚索最大轴力以及地表最大沉降位移的影响规律,最后提出主动区溶洞的处理方法。结果表明:最危险滑移面的剪出口出现在强风化石灰岩与中风化石灰岩的分界线处,最危险滑移面为与基坑内壁夹角约45°方向的弧形面;在同一溶洞中心埋深下,越靠近最危险滑移面的溶洞对基坑稳定性影响越大,当溶洞中心埋深不同但都在最危险滑移面上时,越靠近剪出口的溶洞对基坑稳定性影响越大;溶洞边长越大,对基坑稳定性影响越大,当边长大于等于2 m时,需要对溶洞进行处理,且利用增大锚索预应力的处理方法对主动区溶洞的处理效果比较明显。可见,考虑最危险滑移面的不利影响对研究主动区溶洞对桩锚支护基坑稳定性的影响是必要的。In order to study the influence of karst cave in active area on the stability of pile anchor supporting foundation pit when there is the most dangerous sliding surface,FLAC3 Dsoftware was used to simulate the position of the most dangerous sliding surface when there was no karst cave,and then the influence of different locations and sizes of karst caves in active area on the maximum horizontal displacement and bending moment of pile,the maximum axial force of anchor cable and the maximum settlement displacement of ground surface were simulated respectively.Finally,the treatment method of karst cave in active area was proposed.The results are listed as follows.Firstly,the cutting outlet of the most dangerous slip surface appears at the boundary between strongly weathered limestone and moderately weathered limestone,and the most dangerous slip surface is a curved surface with an angle of about 45°to the inner wall of the foundation pit.Secondly,in the same cave center under the buried depth,the cavern closer to the most dangerous slip surface has a greater impact on the stability of the foundation pit.When the cave center has different buried depths but all on the most dangerous slip surface,the cave closer to the shear outlet has a greater impact on the stability of the foundation pit.Thirdly,the larger the side length of the karst cave,the greater the impact on the stability of the foundation pit.When the side length is greater than or equal to 2 m,the karst cave needs to be treated,and the treatment method of increasing the anchor cable prestress is more effective in treating the karst cave in the active zone.It is concluded that it is necessary to consider the adverse effects of the most dangerous slip surface to study the influence of karst caves in the active zone on the stability of pile-anchor foundation pits.

关 键 词：最危险滑移面 溶洞 基坑 锚索预应力 

分 类 号：TU753[建筑科学—建筑技术科学]