Various analytical solutions have been proposed for a unit-cell consolidation with a vertical drain under surcharge loading. These solutions involve different assumptions to address various aspects of consolidation. There is a lack of generalised solution for analysing consolidation of soil assisted by a vertical drain under various loading conditions. This paper presents a simplified solution for consolidation under multi-ramp loading. Generalised governing equations of equal-strain consolidation are solved. Simultaneous radial and vertical flow conditions, as well as the combined effects of drain resistance and smear, are taken into account fully. An increase in total stress due to multi-ramp loading is reasonably modelled as a function of both time and depth. An analytical solution to calculate excess pore-water pressure at any arbitrary point in soil is derived by using the method of separation of variables. The conventional definition of the degree of consolidation is given in terms of the dissipation of excess pore-water pressure as a result of the maximum increase in total stress in soil. This definition is interpreted in relation to the ultimate ground surface settlement due to surcharge preloading. Its validity and accuracy are verified by comparing the special cases of the proposed solution with two available analytical solutions. The proposed solution is also validated by a welldocumented case history with settlement and pore-water pressure measurements. Reasonably good agreement is obtained. A new degree of dissipation is defined in terms of the dissipation of excess porewater pressure as a result of currently induced increase in total stress in soil. By using this definition, an equation is proposed to estimate the gain in undrained strength of soil due to consolidation for assessing the stability of surcharge fills more effectively and correctly. The loading path over time and the compressibility of smeared soil are shown to have a potentially important influence on the degree of consolidation and the degree of dissipation.

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Pipeline transportation plays a vital role in the transportation of oil and gas. The safety monitoring of pipeline transportation is essential in pipeline operation. Distributed optical fiber sensing technology has more advantages than other conventional pipeline security monitoring method. The ability to measure temperatures and strain at thousands of points along a single fiber is particularly meaningful for the monitoring of pipeline transportation. This paper introduces the principle of distributed optical fiber sensing technology in temperature and strain measurement. DiTeSt (Distributed Temperature and Strain) monitoring system based on Brillouin scattering is used in the monitoring project of Andes pipeline and Italy Rimini gas pipeline for example to detect the geological hazard around pipeline and monitor the deformation and leakage of pipeline. The pipeline monitoring system has been well used in the safety monitoring project of high altitude and long distance pipeline transportation. It shows that DiTeSt(Distributed Temperature and Strain) monitoring system is capable of warning pipeline disasters, improving the efficiency of pipeline transportation safety monitoring, ensuring the normal pipeline transportation safety operation and reducing the property loss of operator.

This paper summarizes the current treatments and countermeasures for liquefiable foundations, and divides the existing anti-liquefaction countermeasures into two categories. One of the ideas is proceeding from the properties of liquefiable foundation soils, by the means of improvement for the soil’s qualities to enhance the capacity of soil’s anti-liquefaction in the early stage. The other idea is considering from the stress conditions of liquefiable foundation soils, and to reduce the liquefaction-induced disasters by changing the stress conditions of the soil. The advantages and disadvantages of various anti-liquefaction measures were analysed by verifying the effectiveness of field applications of anti-liquefaction measures against ground liquefaction hazards, and the applicable conditions of various anti-liquefaction measures were classified. This paper provides experience for resisting soil liquefaction disasters.

The nonlinear variation of soil compressibility and permeability with void ratio (i.e., e-log σ′ and e-log k) has been included in the consolidation theory to accurately predict the behavior of soft soil stabilized by vertical drains. However, most current nonlinear consolidation models incorporating the coupled radial-vertical flow are based on some simplified assumptions, while including some features such as the complex implementation of multilayered computations, time-dependent loading and stress distribution with depth. This study hence introduces a novel approach where the spectral method is used to analyze the nonlinear consolidation behavior of multilayered soil associated with coupled vertical-radial drainage. In addition, time- and depth-dependent stress and soil properties at each soil layer are incorporated into the proposed model. Subsequently, the solution is verified against experimental and field data with comparison to previous analytical solutions. The results show greater accuracy of the proposed method in predicting in-situ soil behavior. A parametric study based on the proposed solution indicates that the ratio between the compression and permeability indices (ω = Cc/Ck) has a great impact on the consolidation rate, i.e., the greater the ω, the smaller the consolidation rate. Increasing the load increment ratio and the absolute difference between unity and ω (i.e., |ω − 1|) can exacerbate prediction error if the conventional simplified methods are used.

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