Study On The Influence Of Dynamic Compaction Vibration On The Stability Of Retaining Wall

Dynamic compaction of soils is a wide spread soil improvement technique that has been used with proven effectiveness in the field of geotechnical engineering.It is performed by dropping a given weight from a specified height on the ground.The produced energy transmits compressive wave through the soil layers,which generate vibrations causing the densification of the soils particles.The technique is environmentally friendly and simple to apply,which enabled geotechnical engineer to consider it as one of the primary solutions for densification of weak soil encountered in construction of foundation,highways and embankment.But,the heavy tamping foundation reinforcement in reinforced soil,heavy hammer impact at the same time,also produced a strong vibration in the foundation soil,dynamic compaction vibration spread to fluctuations in soil,causing adverse effects on the field and surrounding environment,and even lead to the destruction of buildings,understand and grasp the dynamic compaction vibration strength and attenuation law in the process of dynamic consolidation,understanding the influence of dynamic compaction vibration on buildings,study the response of buildings to dynamic compaction,determine the safe distance of dynamic consolidation construction relative to the building,it is of great significance for minimizing the negative effects of dynamic compaction vibration on engineering and environment.This paper is based on the UHVDC transmission project of Jin Bei-Jiangsu and Nanjing in Shanxi,study on the action and influence of dynamic compaction vibration on retaining wall.This paper is mainly divided into two parts;the first is the study of vibration wave field of foundation consolidation by dynamic compaction;second is study of the influence of dynamic compaction vibration on the field surrounding retaining wall.Concerning with the research work on vibration field of dynamic compaction the following tasks are mainly carried out;first of all,obtain the relevant geological data and engineering survey and design information of the project,understand the requirements of engineering design for vibration control of dynamic compaction: Then,arrange the test line and analyze the dynamic compaction vibration caused by dynamic compaction,obtain the measured data of dynamic compaction wave field distribution and dynamic compaction attenuation along the test line.Finally,establish the numerical model according to the actual conditions of the field,The distribution of the dynamic compaction wave measured by the test line is taken as the objective function,numerical simulation of dynamic compaction wave field distribution and dynamic compaction vibration attenuation of several typical tamping points on the site of the project is carried out by using GDEM program,obtain some representative compaction points corresponding to the site periphery,data of dynamic compaction wave(rhythm change)action along the planned retaining wall.The main research work on the influence of dynamic compaction vibration on the field outer retaining wall includes: Firstly,the simulation results of dynamic compaction vibration wave field by using representative tamping points,extracting vibration velocity history of retaining wall at the bottom,analyze the characteristics and laws of the effect of dynamic compaction vibration on the field surrounding retaining wall,the effect of dynamic compaction vibration on retaining wall is simplified as quasi static load with rhythmic change;then,according to the size characteristics of retaining wall and the spatial relation of dynamic vibration wave field,the retaining walls simplified to one-dimensional beamsanalyze the stress distribution and deflection of retaining wall under pseudo static load of dynamic compaction.Through the above research,obtain the following results and Knowledge:(1)In the numerical simulation,the retaining wall 200 mlengththe tamping point is located on x directionof the retaining wall 80 mlength on the line from the retaining wall of the vertical distance 30 m,40m and 50 m,a representative of tamping energy 6000 kN.Experimental simulation was found during the process;at the tamping point of 30 m tamping the maximum amplitude of retaining wall is 0.27cm/s,at the tamping point of 40 m tamping,the maximum amplitude of retaining wall is 0.25cm/s,at the tamping point of 50 m tamping,the maximum amplitude of retaining wall is 0.21cm/s.By analyzing the law of retaining wall vibration during dynamic compaction,the vibration waveform and energy can be obtained,the stress characteristics of retaining walls simplified into one-dimensional beams subjected to static dynamic compaction are analyzed.(2)The retaining wall is simplified into a one-dimensional beam,through static load analysis retaining wall in static dynamic loads was shear failure.50 m,40m,30 m tamping point beam at the maximum bending moment is 4535kN?m,8035kN?m,16129kN?m corresponding the normal stress is 0.34 MPa,0.62 MPa,1.22 MPa.Compared with the calculation results,it is found that the 30 m do not meet the requirements,so the safety distance of the retaining wall is 40 m.(3)The retaining wall is less than 30 m,the normal stress of retaining wall is greater than 0.7 MPa retaining walls can all break down.At the same time,the strength of concrete is 0.618 MPa at the age of 19 days and the tensile strength is 0.629 MPa at the age of 20 days.So it is indicated that the concrete can be dynamically rammed at 40 m after the age of the concrete is greater than 20 days.