Helical piles can be rescrewed at greater depths after failure and put back into service again as long as their integrity is preserved. However, reports on the lifetime performance after reinstallation are completely missing in the literature. This work compares the tensile cyclic response of single helix piles in dry and saturated sand after experiencing failure due to monotonic uplift and after reinstallation, using centrifuge model testing. Tensile cyclic tests were conducted on three model piles with different helix-to-shaft diameter ratios, under two different conditions: (1) cyclic loading after monotonic pile failure, and (2) cyclic loading on a pile that has been reinstalled deeper into the soil after experiencing a monotonic failure. The experiments revealed that the preceding monotonic failure causes significant influence on the post-failure cyclic performance, in which few tens of cycles are enough to lead to a critical accumulated displacement. The cyclic tests on the reinstalled helical pile at a depth of 2D (D = helix diameter) below the initial helix depth showed that the cyclic performance can be partially to fully recovered depending on the loading amplitude.

Relating soil moisture content to soil suction, the soil-water characteristic curve (SWCC) represents an essential feature in unsaturated soil mechanics that enables estimation of different unsaturated soil property functions and modeling of the macro-scale soil behavior. However, depending on the soil and processes under consideration, proper hydraulic characterization of a soil through direct laboratory measurements can be difficult, time-consuming, and involve many uncertainties. In the case of uniformly graded sands, there is a highly nonlinear and steep shape of the SWCC, with only a few kPa of soil suction separating saturated and residual soil moisture conditions, which makes measurements for determinations of SWCC especially challenging. This study encompasses an investigation of the sandy type of soil's behavior and presents some preliminary results and experiences on the determination of SWCC through the use of physical slope model tests. The 30 cm deep slope, inclined at 35 degrees and instrumented with soil moisture and pore water pressure sensors, was exposed to series of rainfall intensities, ranging from 37 up to 300 mm/h. The results indicated that the data on hydraulic response in monitored points are not only useful for the determination of SWCC, but that the approach is useful for investigation of hydraulic hysteresis phenomena, as well as its effects on soil moisture and pore water pressure conditions, which also affects the stability conditions of a slope. In particular, the best-fit parameters of the van Genuchten model suggested air entry values of 1.6 and 1.1 kPa for the drying and the wetting curves of the SWCC, respectively, with the two branches shifted by about 1 kPa of soil suction.

In modern construction projects, a significant challenge arises from the consequential impacts of developing adjacent structures. The interplay of stresses within neighboring foundations can lead to a range of issues, such as deformation, leaning, cracking, instability, and various other damages. Among the numerous factors affecting foundation interaction, this research uniquely focuses on the impact of soil type, utilizing precise physical modeling through a 1 g testing apparatus. To enhance measurement accuracy, image processing techniques are employed in conjunction with LVDT and displacement gauges. The study systematically investigated the roles of five distinct deposit types -soft clay, loose sand, silty sand, loess, and low-compacted Tehran clay -in the manifestation of settlement and tilt arising from foundation adjacency. Subsequent to this evaluation, a comprehensive examination of strategic measures aimed at preventing and mitigating damages resulting from foundation interaction is undertaken. For silty sand, a detailed comparison of five remediation techniques is conducted, while in other soil types, only densification method is applied to address settlement and tilt. The comparison is based on the reduction in settlement and tilt, after the implementation of remediation methods under new foundation. Results highlight the crucial role of soil properties in determining damages from foundation adjacency. Notably, Tehran soil with low density exhibits maximum settlement in its loose state, while loess soil shows the highest settlement in the dense state. The exploration of soil improvement methods reveals that diaphragm walls and pile groups are influential in minimizing tilt and settlement of existing foundations, while pile groups proved to be the best remediation method in controlling displacements of new foundation.

This paper presents a series of results of landslide model experiments with different rainfall conditions, including the observation of progressive failure on the slope surface, pore water pressure, and soil pressure inside the body. The influence of intermittent and continuous rainfall on the stability of homogenous slope is discussed. On this basis, we construct a numerical model in FLAC(3D) to reproduce the process of model tests. Different rainfall factors that affected the stability of landslide are analyzed along with the model test results. The pore water pressure and soil pressure in the slope increase in proportion with rainfall under both rainfall conditions. The descend order of pore water pressure growth rate is slope middle, slope top, and slope toe. Compared with the pore water pressure in the middle slope under different conditions, the value of intermittent rainfall test is 21.9% higher than that of the continuous rainfall test. On the one hand, pore water pressure exhibits a cumulative effect under the intermittent rainfall condition. On the other hand, pore water pressure, horizontal tensile stress, and maximum displacement increase proportionally with the rainfall intensity under the same rainfall condition. The rainfall with low rainfall intensity is more likely to form infiltration in slope, whereas the high rainfall intensity one has obvious influence on the slope stress field. When the rainfall intensity reaches 30 mm/h, the increase in rainfall intensity can no longer affect the horizontal stress distribution of the slope significantly. Instead, it shows a greater impact on the failure mode of the slope, and the erosion occurs on the surface of the slope.

This work physically simulates the effect of low and high flow rates and filling times of reservoirs and rupture due to overtopping (caused by intense rains) of small homogeneous silty-sand earthfill dams. The experiments seek to verify how input variations impact the formation of the breach and the rupture wave. The results show that different filling times, soil moisture and composition, and degree of compaction affect landfill saturation, failure time, and breach formation. The result confirms that smaller breaches with a higher degree of compaction led to a lower peak rupture flow compared to dams with low degree of compaction. The rupture hydrograph presents a faster descent stage than an exponential hydrograph. Simulations and models based on this law may minimize the effect of the dam-break wave, also impacting water resource decision-making for damage reduction. The results were extrapolated to a real prototype, providing information and a database for the studies of overtopping dam-break waves.

As vital hydraulic infrastructure, barrages and canals are crucial for agricultural irrigation in Sindh Province, Pakistan. Any deviation from the intended design discharge can significantly impact water resource management, leading to economic losses. The Ghotki Canal in Sindh faced challenges in receiving its allocated inflow, prompting an extension of the divide wall at Guddu Barrage to 589.59 ft. However, this extension inadvertently exacerbated the problem by reducing the Ghotki canal's inflow, resulting in a 166.7 ft gap between the original and extended divide wall segments. This study takes a unique approach, using a non-distorted physical model at a scale ratio of 1:85, to assess the influence of the divide wall gap across five scenarios, varying gap width and river flow rates from 100,000 to 500,000 cusecs. The findings highlighted the disruptive effects of the gap on flow regimes, notably affecting critical infrastructure such as the silt excluder and left pocket capacity. Alterations in the divide wall gap width predominantly impact the Ghotki Canal discharge while minimally affecting the Rainee Canal. Without a divide wall gap, the Ghotki Canal's head regulator draws 88% of the designated capacity, while the Rainee Canal consistently receives its total inflow share of 10,000 Cusecs. In conclusion, this study underscores the importance of structure remodeling in barrages for effective water resource management, emphasizing the need for nuanced approaches to optimize canal performance and sustain agricultural livelihoods and regional development. This study examines divide wall and gap impacts on canal water flow by physical modeling. The study assesses challenges in water allocation efficiency. This study offers insights into the change in flow behavior due to the divide wall gap.