Study On Supporting Technology Of Fluid Filling Lining In Deep Soft Rock Tunnel

In recent years,with the rapid development of China's economic construction and the increase of investment in infrastructure construction,the scale and depth of underground engineering in the nuclear industry,national defense industry,communications and water conservancy and other industries are growing at a high speed,and geotechnical engineering is developing to the depth.Tunnel engineering at home and abroad is more and more involved in high in-situ stress and deep rock mass areas.Due to the stress redistribution of excavation unloading,the problems of large creep variable(>100cm),long creep time(>3 years),and uneven lining stress are still emerging in deep diversion tunnel engineering and traffic tunnel engineering under complex geological conditions.According to this,this paper carried out deeply soft cave room liquid filling lining support technology experiments,can be in the process of the surrounding rock creep stress homogenization lining at the same time give a certain amount of surrounding rock deformation space(30 cm ? 50 cm)and to provide the specified surface type supporting force,greatly reduce total creep of surrounding rock and loose circle development degree and extension of plastic zone.In order to quantitatively analyze the supporting effect and supporting mechanism of fluid filling lining supporting technology,a series of tests were carried out.The specific research results are as follows:(1)The law of load reduction and the law of stress homogenization under the action of partial pressure of filling material1)In the process of lateral compression,the compression rate of 8mm soil reaches 16%,which is 6.67 times that of fine sand.The fine sand can provide a larger space for compression and deformation.In the process of compression,the uneven settlement of soil particles produces local "soil arch effect",which changes the force transmission range of the filling material inside the lining.2)In the process of lateral compression,the fine sand has a low compression rate and a small particle size.The settlement at all points in the same layer is basically the same,and the pressure at the bottom increases uniformly.The homogenization effect is remarkable.(2)Research on non-newtonian fluid filling lining support technology-long-term stability test1)The settlement deformation in the loading process is divided into three stages: rapid deformation section,slow deformation section and stable stage;Three types of initial water content silt capsules are divided into plastic state and flow plastic state.2)The overall unloading load of 80% moisture content silt is about 3.25 times that of 40% moisture content silt,and the unloading effect is remarkable.With the increase of moisture content in silt,its liquidity increases with the bearing capacity is abate,makes the top pressure of peak clipping lightening effect significantly,the horizontal dispersion stress rate faster,easier to a level to the top of the vertical pressure,they can select proper moisture content according to the needs of practical engineering mud as a buffer layer immediately modifies the two lining structure.3)In the stable loading section with different water content,the compression amount of silt-bag lining increased with the load,and the final settlement amount reached 7.5cm,not much different from the settlement value in the loading stage,with a maximum difference of 0.04%,indicating that the anti-support force of silt-bag lining structure can remain stable for a long time in the long-term pressurized environment.(3)Research on the technology of non-Newtonian fluid filling lining-simply supported beam test of silt-bag lining1)Beam compared to the moisture content of 40% across the maximum deflection of the silt capsule type lining by 37.7%,maximum pressure value relative to the beam span of 4 points of maximum pressure value by 87.83%,60% maximum deflection in silt capsule type lining across most reduced by 10.6%,the maximum pressure relative to the beam span of 4 point maximum pressure was reduced by 85.62%,and with the increase of load of silt capsule type lining trend lower than the midspan deflection of simply supported beam with simply supported beam with large,lightening effect is remarkable.2)The load homogenization effect of 60% moisture content silt bag lining is about 28% that of 40% moisture content silt bag lining.3)Across from the mechanics analysis and 1/4 span deflection of mud pressure beam order growth rate was > 40% moisture content > 60% moisture content of sludge,across the deflection and stress sort growth rate at 60% moisture content sludge silt > > 40% moisture content without buffer layer lining of simply supported beam,shows that silt capsule type masonry structure will load from more stress homogenization to force smaller location,show that silt capsule type lining structure stress larger position of pressure load growth rate greatly reduced,and the moisture content of high silt reduction is the largest.4)Under the same condition,the support effect,load reduction homogenization effect and fluid discharge effect of silt are better than that of solid fluid lining,and the partial instantaneous unloading rate is as high as 90.5%.The transition of flow-plastic state-solid-plastic state can be realized freely.5)Compared with previous studies,sand filling type lining type silt sac lining beam test across encrypted to decorate,monitoring points in the test range is more meticulous,comparative analysis the early stage of the liquid filling lining structure related experimental results,show that silt capsule type lining in practical engineering is generally applicable to shock under the effect of the actual project,the impact effect in the practical engineering under the silt capsule type lining structure is suitable for the local large deformation of surrounding rock location,mainly to force the homogenization of unloading and peak clipping lightening effect.6)A pressure distribution model is established and the formula for calculating the distributed force work of channel steel subjected to silt-bag lining homogenization is given.(4)Based on CT imaging the plastic zone and mechanical response of surrounding rock under different supporting forces1)A preliminary study on the internal stress in the stress accumulation area with a maximum capacity of 50 Mpa and the deformation,pressure and self-deterioration degree of the stress accumulation area with or without the stress locking force also shows that the supporting structure exerts a significant inhibitory effect on the surrounding rock plastic area in time,which proves the feasibility of the method to simulate the high-in-situ stress soft rock.2)The test results show that compared with the rigid support,the fluid lining can provide A certain deformation space for the surrounding rock face while effectively inhibiting the development of the plastic zone in the surrounding rock.It can not only effectively support the increasing ground stress,but also slowly release part of the ground stress,and can effectively homogenize the surrounding rock loose zone development to make the plastic zone flat,homogenized.