Papers by Keyword: Dynamic Compaction

Abstract: In order to provide the reference and basis to construction scheme and post-construction settlement prediction, this article based on a dynamic compacted red soil foundation of large-scale oil tank first-stage project of Guangxi, took settlement and conical surface deformation observation and used consolidation degree logarithm method to predict the final settlement of red soil foundation. According to the research, the effect of dynamic compaction was promising, and this method provided a reference to settlement prediction of red soil foundation.

Abstract: To find the influence of the layout of punning position in dynamic compaction for loess, four model tests are performed, which equal in the tamping energy but differ in the layout of punning position. In model tests the settlement, the dry density and the shear strength parameters of the soil samples are measured and analysis of the effects of different test plans is made. The test results manifested that the decrease of the distance between the pounding points might result in an increment of the settlement, the dry density and the cohesive strength but not the angle of internal friction. And from the comparison of the test results, a more efficient layout of punning position is given.

Abstract: As a convenient and rapid nondestructive testing method, transient Rayleigh wave has an increasingly wide range of applications in engineering, and the testing result is increasingly accepted in the engineering domain. With engineering examples, this article mainly analyzed the nondestructive testing principle and detected the data processing method. By analyzing the engineering example that using transient Rayleigh wave method to detect the effect of dynamic compaction about foundation, the conclusion that transient Rayleigh wave could conveniently and rapidly detect the effect of dynamic compaction about roadbed of the expressway was farther proved, which has certain provide engineering significance for the future engineering detection.

Abstract: While widen the highway foundation, due to it is still unclear that the law of dynamic compaction vibration impact on the original subgrade and foundation structure , which restricts the use of dynamic compaction technology in the highway foundation-broaden project. In this paper, by using the dynamic compaction indoor model test, simulated the dynamic compaction road widening foundation works, monitored the vibration acceleration of the pavement and subgrade surface in the process of dynamic compaction vibration, analyzed the dynamic compaction vibration propagation law of the roadside foundation in the subgrade structure. At the same time, we made the vibration amplitude of the key points and the rammer subsoil dynamic pressure value as double assessment indicators. Besides, we analyzed the dynamic compaction vibration response of subgrade under different parameters, evaluated foundation reinforcement effect. With research, under the same tamping energy and in a certain range of rammer diameter and weight, we had better choose small radius rammer and the compaction process of heavier rammers dropping from lower point, which can reduce the foundation dynamic vibration of the old subgrade and ensure foundation reinforcement effect.

Abstract: Damping ditch was dug beside the underground pipeline so as to prevent housing from damage and reduce displacement of underground pipelines caused by dynamic vibration. Different damping ditches were simulated and field measurement was tested. Research shows that vibration and squeezing effect cannot be neglected, and damping ditch can decrease the vibration and squeezing effect. The deeper and nearer to the housing the damping ditch is, the better the damping effect is. The underground pipelines displacement is slight, when the damping ditch is between underground pipelines and tamping points and much closer to the former. Otherwise, if the damping ditch is considerably closer to the tamping points, the displacement is comparatively large.

Abstract: The effective reinforcement depth is one of the most important parameters of dynamic compaction method design and construction, so far it is still lack of in-depth theoretical study. In this paper, combined with the field test, FLAC3D was used to do the numerical simulation of dynamic compaction reinforcement to cohesionless soil. By the simulation, this paper analyzed the factors which may influence the effective reinforcement depth, such as the hammers weight, drop distance, base area, and the soil parameters. The orthogonal design method was used to analyze the soil parameters sensitivity to the effective reinforcement depth. Combined with the results of numerical analysis and the traditional empirical formulae, the effective reinforcement depth calculation formula was established for cohesionless soil. Engineering verification shows that, the results estimated by the formula is reliable, and can provide certain reference for the future engineering.

Abstract: According to the dynamic compaction project of Beijing Garden EXPO Park, an experiment is designed to monitor the deformation and vibration range impact by dynamic compaction.The vibration velocity, vibration acceleration, settlement and deep horizontal displacement of the foundationare obtained through the continuous real-time monitoring during the experiment.In this paper, the expression of vibration velocity and acceleration decreased by distance is established according to the experimental data, besides, the relation ofsingle settlement and total settlementof tamp pit changed with hit numbers is also achieved.The study shows that,under the 3000kJ compact energy,the settlement range is about a circle with radius12.7m; the deep horizontal displacement changes only in range of radius 7.7m; the safety distance of vibration is 47.7m, and to fulfilling the requirement of consolidation 7 hits is appropriate. The study provides a reference to dynamic compacting processof this project.

Abstract: Using DPT and plate loading test, the paper analyzed different reinforcement effects from four different reinforcement technologies－gravel piles method, dynamic compaction method, dynamic compaction replacement (DCR) method and impact compacted method for Cha-Ge highway saline soils ground located in salt lake area, and got the following conclusions: (1) DCR method has the best reinforcement effect, and impact compacted method has the worst. There is a difference of 166.9 % between them. (2)Tamping energy is important on reinforcement effect to the last three methods and related directly to the values of the strengthened bearing capacity and deformation modulus. The DCR method and gravel piles method mentioned above are useful on reducing the settlement of natural saline soils foundation. In recent years, a lot of ground treatment methods are widely used to consolidate soft soil foundation for its short period and simple construction and so on. Numerous scientists and engineers have obtained useful results and experience from DCR and gravel piles foundation treatment of soft soil [1,2,3,4]. (e.g., A. G. Phear, S. J. Harris, 2008; Dong,Yan and , 2009; Huang, Zhou and He, 2006; Liu, 2006;); But the reinforcement in regions of saline soils, such as DCR hasn't been well researched; theoretical study is far behind engineering practice; so it is hard to build up the design theory and method..

Abstract: This paper described the working principle of dynamic compaction and the main points of construction, Using degree of compaction and deflection, evaluating construction quality based on actual project. we can solve the problem of construction quality of the road bed effectively and the waste of the dust, thus avoiding the environment pollution of waste dust and make a good economic and social profit.

Abstract: Combined with the dynamic compaction example of a nuclear power plant, a fully field tests was conducted to get the permeability and integrality of the impervious wall in real time. The dynamic compaction vibration impact on impervious wall was researched based on the test results. The relationships between damage characteristic and peak particle velocity of impervious wall are suggested also. The safety control standards which used vibration safety threshold to control the potential damage for impervious wall under long-term dynamic compaction were presented. When the PPV of impervious wall is not exceeding the safety threshold, the impervious wall will in its secured state. According to the damage detection method and the presented safety threshold of vibration velocity, the protected structure can be simply and protected during dynamic compaction. The research methods reflects the damage of protected structure directly, and more accurate and safety than traditional methods.