Using fracture grouting to lift structures in clayey sand

An inclined seven-story reinforced concrete building was leveled by a fracture grouting technique with quick-setting grout on a differential thickness of a clayey sand layer. The permeability and strength of clayey sand were controlled by clay content, although sand was the primary component of the foundation soil. The elevations of the building columns at basement level were closely monitored to record both the heaved volume of mat foundation after grouting and the settled volume during pore pressure dissipation. During the stabilizing stage of grouting, the foundation soil was densified by the repetitive fracturing process, which resulted in the lateral movement of the foundation soil. When the grout is less able to push soil laterally than upwards, the building starts to lift, the so-called lifting stage of grouting. The grouting efficiency is influenced by soil type, soil stress history, and foundation pressure. A final grouting efficiency of 27% and a linear relationship between grout use and percentage of eleva-tion were obtained when this building was successfully and permanently leveled.

Predicting jet-grout column diameter to mitigate the environmental impact using an artificial intelligence algorithm

This paper describes an approach for predicting the diameter of a jet-grout column using the support vector regression(SVR)technique,which is regarded as a novel learning machine based upon recent advances in statistical theory,in which the combined effects of the construction(construction methods and jetting parameters)and soil properties(soil type and shearing resistance)are considered.Four different kernel functions,namely,a linear kernel function,polynomial kernel function,radial basis kernel function,and sigmoid kernel function,are integrated into the SVR technique.A large amount of field measured data on the diameter of jet-grout column are retrieved from the published literature for training and testing purposes.The results indicate that the SVR technique with a radial basis kernel function provides predictions closest to the measured results,whereas the prepared design charts enable the ability to significantly widen the application of the proposed approach to the areas of ground improvement and environmental protection.

Variation of hydro-environment during past four decades with underground sponge city planning to control flash floods in Wuhan,China:An overview

This paper presents a review of the variation in the hydro-environment over the past four decades in Wuhan,China,and discusses its close relationship with flash flood events.These flash flood events have inundated underground infrastructures and resulted in significant economic losses and casualties,which are also discussed in relation to various external and internal factors.The external factors are predominantly owing to heavy rainstorms resulting from extreme climate change.The internal factors predominantly include a decrease in wetland areas,changes in topography,and disrepair of drainage systems in urban areas.Since the 1970s,lakes in Wuhan have been significantly reduced in size(by approximately 40%).This reduction in wetland area decreases the water storage capacity in urban areas,and the frequency of large flooding events thus increased from 0.1 event/year to approximately 0.2 event/year.Additionally,the disrepair of drainage systems in urban areas has reduced their ability to resist flood hazards.Changes in topography have also intensified the flood volume per unit time,further burdening the drainage systems.In 2016,Wuhan suffered from several large flooding events that led to some of the most severe economic losses in recorded history.The drainage system at the urban center of Wuhan and proposed flood prevention methods are discussed in detail in this paper.The sponge city(SPC)concept has been attempted in Qingshan District,Wuhan,and its success proved the reliability of the theory.A SPC is believed to reduce the impacts of future flash floods in China and other developed and developing countries.