Analysis Of The Mechanical Behavior Of Digging Foundation In Rocks

The excavation foundation is between the open excavation foundation and the settlement foundation.The foundation pit construction emphasizes vertical excavation.The buried depth is generally controlled within 15 m.The cross-sectional area far exceeds the general pile foundation and mainly depends on the end bearing.The well digging foundation has high bearing capacity,small settlement and strong anti-overturning ability,and has many engineering applications in the northwest loess area.With the construction of the transportation network in the southwest mountainous areas,narrow environments such as cliffs and steep slopes have restricted the use of general pile foundations,and excavated well foundations can be well adapted to such environments by increasing the buried depth.At present,the engineering application of the well digging foundation has achieved good results,but the relevant literature research is relatively small.The buried depth of the well digging foundation in the southwest region exceeds 15 m,and the medium is mostly soft rock mountains.These two changes affect the well digging foundation.What kind of influence the force will bring needs to be researched and summarized.In this paper,through a large number of literature investigations,the pile-rock mechanics model is used for reference,and the stress analysis of the rock excavation foundation is carried out.The research work and results achieved are as follows:(1)The rock digging foundation has a large burial depth,and is mostly installed in soft rock mountains.The burial depth and medium environment are different from the loess digging foundation.After referring to the relevant literature of rock-socketed pile and loess digging foundation,it is clear The lateral resistance of the rock excavation foundation cannot be ignored.The lateral resistance and the end resistance share the vertical load.The side wall contact can be analyzed by pile-rock contact.(2)By relying on the numerical simulation of the rock excavation foundation of the project,the influence of the construction of the upper part of the foundation on the foundation is analyzed,and the accuracy of the model is verified by the on-site measured data and the theoretical formula for reference.Relying on the large buried depth of the project,the load shared by the side resistance is more,and the end resistance accounts for only 36.46%,showing the nature of friction piles.(3)The effects of parameters such as burial depth,diameter,cross-sectional shape,cohesion,internal friction angle,media stiffness,and load size on the vertical bearing of rock excavation foundation were studied.By analyzing the PS curve,axial force curve,friction resistance Curves and contact pressures draw relevant conclusions.For rock excavation foundations,it is difficult to effectively reduce the settlement by increasing the burial depth,and appropriately increasing the diameter can effectively reduce the settlement;the cross section of the rock excavation foundation should be rounded,and the increase of the vertical load will increase the end resistance ratio;medium The effects of stiffness,cohesion,and internal friction angle on rock excavation foundations are consistent with existing pile foundations,but the impact is not as obvious as pile foundations.(4)Establish a foundation model for rock excavation in the cliff environment,apply a horizontal displacement of 0.01 m to the top surface of the foundation,and study the influence of burial depth and cross-sectional shape on the horizontal bearing capacity.By analyzing the horizontal displacement curve,section shear curve,section bending moment curve,it is found that increasing the buried depth can improve the horizontal bearing capacity of the rock excavation foundation,but excessively increasing the buried depth cannot significantly increase its horizontal bearing capacity;the round end shape The horizontal bearing capacity of the well digging foundation is the highest.When the top surface of the foundation is at the same horizontal displacement,the top surface bears the highest shear value and bending moment value.