Effect Of Wetting-drying Cycles Research Articles

Effects of bacterial strains on undrained cyclic behavior of bio-cemented sand considering wetting and drying cycles

The microbial-induced calcite precipitation (MICP) technique has been developed as a sustainable methodology for the improvement of the engineering characteristics of sandy soils. However, the efficiency of MICP-treated sand has not been well established in the literature considering cyclic loading under undrained conditions. Furthermore, the efficacy of different bacterial strains in enhancing the cyclic properties of MICP-treated sand has not been sufficiently documented. Moreover, the effect of wetting-drying (WD) cycles on the cyclic characteristics of MICP-treated sand is not readily available, which may contribute to the limited adoption of MICP treatment in field applications. In this study, strain-controlled consolidated undrained (CU) cyclic triaxial testing was conducted to evaluate the effects of MICP treatment on standard Ennore sand from India with two bacterial strains: Sporosarcina pasteurii and Bacillus subtilis. The treatment durations of 7 d and 14 d were considered, with an interval of 12 h between treatments. The cyclic characteristics, such as the shear modulus and damping ratio, of the MICP-treated sand with the different bacterial strains have been estimated and compared. Furthermore, the effect of WD cycles on the cyclic characteristics of MICP-treated sand has been evaluated considering 5–15 cycles and aging of samples up to three months. The findings of this study may be helpful in assessing the cyclic characteristics of MICP-treated sand, considering the influence of different bacterial strains, treatment duration, and WD cycles.

Experimental Study on the Effect of Wetting-Drying Cycles on Crack Development and Radon Retardation of the Covering Soil in Uranium Mill Tailing Impoundments.

The majority of uranium mill tailing impoundments in the southern part of China are located in humid subtropical regions where persistent rainfall and rapid evaporation of water after rain often occur. Under the prolonged influence of alternating wet and dry conditions, the covering soil layer of uranium mill tailing impoundments develops cracks, leading to the issue of degradation or even failure of the radon retardation effect. A beach surface of uranium mill tailing impoundments in the southern part of China is selected as the research object. Through use of a self-made simulation test device, a degradation experiment of uranium mill tailing covering soil models under wetting-drying cycles was conducted indoors. The experimental results indicate that with a constant amplitude of wetting-drying cycles, microcracks characterized by a narrow width and high abundance were mainly generated in the early-to-mid-stage of wetting-drying cycles. The main cracks, characterized by their wide width and less abundance, were mainly formed in the mid-to-late stage of wetting-drying cycles. After seven wetting-drying cycles, the total length of cracks showed a "stair-step" increase and the surface crack ratio exhibited a trend of moving from rapid growth to stable growth and then to a slight decline. The cumulative damage degree showed a rapid increase to stable growth with an increase in the number of wetting-drying cycles. Grey relational analysis revealed that, compared to other surface crack indicators, radon exhalation rate was the most closely correlated with the surface crack ratio. With a constant amplitude of wetting-drying cycles, the radon exhalation rate underwent four stages as the number of wetting-drying cycles increased: stage I witnessed a rapid increase, stage II witnessed a rapid decrease, stage III witnessed a gradual increase, and stage IV witnessed a stable or even slight decrease. With a constant number of wetting-drying cycles, the radon exhalation rate correspondingly increased with the amplitude of wetting-drying cycles, particularly noticeable when the alternation amplitude was 30 ± 20%. From the early mid-stage to the late stage of wetting-drying cycles, the curves of the radon exhalation rate, surface crack ratio, and cumulative damage degree tended to be consistent, showing a gradual increase. The research provided in this study offers valuable insights into radon control measures and environmental assessments on the beach surface of uranium mill tailing impoundments.

Spatiotemporal dynamics and modeling of thiacloprid in paddy multimedia systems with the effect of wetting-drying cycles

The widespread presence of thiacloprid (THI), a neonicotinoid, raises concerns for human health and the aquatic environment due to its persistence, toxicity, and bioaccumulation. The fate of THI in paddy multimedia systems is mainly governed by irrigation practices, but the potential impacts remain poorly documented. This study investigated the effects of water management practices on THI spatiotemporal dynamics in paddy multimedia systems by combining soil column experiments and a non-steady-state multimedia model. The results indicated the wetting-drying cycle (WDC) irrigation reduced THI occurrences in environmental phases (i.e., soil, interstitial water, and overlying water) and accelerated the THI loss through the THI aerobic degradation process. THI occurrences in the soil and water phases decreased from 18.8% for conventional flooding (CF) treatment to 9.2% for severe wetting-drying cycle (SW) treatment after 29 days, while the half-lives shortened from 11.1 days to 7.3 days, respectively. Meanwhile, the WDC decreased THI outflow from leakage water, which reduced the THI risk of leaching. There was no significant difference in THI plant uptake and volatilization between CF and WDC treatments. The mean proportions of THI fate in paddy multimedia systems followed the order: THI degradation (57.7%), outflow from leakage water (25.5%), occurrence in soil (12.4%), plant uptake (3.4%), occurrence in interstitial water (0.7%), occurrence in overlying water (0.3%), volatilization (<0.1%) after 29 days. The sensitivity analysis identified the soil organic carbon partition coefficient (KOC) as the most sensitive parameter affecting THI's fate. In addition, the topsoil layers of 0–4 cm were the main sink of THI, holding 67% of THI occurrence in the soil phase. The THI occurrence in interstitial water was distributed evenly throughout the soil profile. These findings made beneficial theoretical supplements and provided valuable empirical evidence for water management practices to reduce the THI ecological risk.

Effects of Wetting-Drying Cycles on the CT-Measured Macropore Characteristics under Farmland in Northern China

Effects of Wetting-Drying Cycles on the CT-Measured Macropore Characteristics under Farmland in Northern China

Effect of Wet-Dry Cycles on the Mechanical Performances and Microstructure of Pisha Sandstone

The effects of the wet-dry cycles on the chemical compositions, microstructure, and mechanical properties of Pisha sandstone were experimentally investigated in the current study. A series of uniaxial compression tests were conducted to validate the deterioration of the mechanical property of specimens after wet-dry cycles. In addition, the evolutions of the mineral compositions and microstructure characteristics were confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Experimental results indicated that with the increase of wet-dry cycles, the mechanical properties of Pisha sandstone gradually decrease. After five wet-dry cycles, the uniaxial compressive strength, elastic modulus, and fracture energy of specimens were reduced by 41.06%, 62.39%, and 31.92%, respectively. The failure mode of the specimen changes from inclined shear failure to peel failure. Compared to the initial specimens, the relative content of primary minerals after five wet-dry cycles declined by 5.94%, and the relative content of clay minerals after five wet-dry cycles increased by 54.33%. Additionally, the porosity of samples exhibits a positive correlation with wet-dry cycles. Compared to the initial specimens, the porosity of specimens after five wet-dry cycles increased by 176.32%. Finally, a prediction model of the correlation between uniaxial compressive strength and porosity is proposed and verified.

Experimental and numerical analysis of CFRP-concrete joint bond behavior after exposure to wet-dry cycles

Fiber-reinforced polymer (FRP) composites have been largely used for strengthening and retrofitting reinforced concrete members in the last few decades. However, limited information is available regarding their performance after prolonged exposure to different environmental conditions. In this paper, the effect of wet-dry cycles on the bond behavior of carbon FRP-concrete joints tested using a single-lap direct shear test set-up is investigated. Specimens were exposed to 50 wet-dry cycles, each comprised of 6 h of immersion in water at 25 °C followed by 18 h of drying at 50 °C. The digital image correlation technique was used to obtain the displacement field of the composite and determine the cohesive material law and fracture energy of the FRP-concrete interface. A finite element model was then used to reproduce the load response and reinforcement strain profile observed experimentally. The results show that wet-dry cycles affect the FRP-concrete bond properties and change the failure mode from a cohesive debonding within the concrete substrate to an adhesive debonding within the interface.

Wetting-drying cycle effect on the compressibility of lime-treated soil accounting for wetting fluid nature and aggregate size

The durability, which refers to the ability of earthen structures to ensure their functionality over time while maintaining their required mechanical performance, is a key issue in evaluating the effectiveness of lime treatment. In this study, the effect of wetting-drying cycles on the compressibility and the microstructure was investigated with lime-treated/untreated samples considering the wetting fluid and the maximum aggregate size (S0.4, Dmax = 0.4 mm; S5, Dmax = 5 mm) effects. Results showed that the wetting-drying cycles caused an increase of void ratio and changed the bi-modal porosity to tri-modal characteristics for the untreated samples, while it led to a reversible variation of void ratio and an unchanged bi-modal pore size distribution characteristics for lime-treated samples, indicating the soil improvement by lime treatment. Thereby, the wetting-drying cycles made the compression curve of untreated samples change from convex to linear shape, while their effect was visible but not significant for the lime-treated soil. Higher decrease of macro-pore void ratio with loading was obtained on the lime-treated samples under wetting-drying cycles compared to the as-compacted samples, indicating a slight softening of soil structure by the wetting-drying cycles. Regarding the effect of wetting fluid nature, synthetic seawater resulted in a higher compressibility than deionised water. This was attributed to the presence of higher quantity of macro-pores in the samples wetted by synthetic seawater induced by the shrinkage of clay fraction. The aggregate size had slight effect on the compressibility of as-compacted samples due to their similar production of cementitious compounds and matric suction. Nevertheless, after wetting-drying cycles, the lime-treated samples S5 had lower decrease of macro-pore void ratio than the lime-treated samples S0.4, due to the significant reduction of macro-pore population with wetting-drying cycles.

Compression behavior and structure of undisturbed Q2 loess under wet-dry cycles

In the Loess Plateau of China, the undisturbed Q2 loess is in a state of wet-dry cycles due to seasonal rainfall and groundwater level fluctuations. The root cause of large deformation and poor stability of engineering foundation caused by wet-dry cycles or load compression lies in the distinctive structure of loess. In this paper, the effects of wet-dry cycles and initial water content on the compression deformation and compression coefficient of undisturbed Q2 loess were analyzed. Based on the structural parameter at the macro-level and the microscopic morphology and pore size distribution at the micro-level, the effects of wet-dry cycles and initial water content on the structure were analyzed from two aspects, and the influence mechanism was discussed. Meanwhile, based on the relationship between microstructure and unsaturation, the impact of wet-dry cycles on the soil–water characteristic curve was determined. The results show that the wet-dry cycles and initial water content were positively correlated with the compression deformation and compression coefficient of the undisturbed Q2 loess, but negatively correlated with the structural parameter and water retention. These parameters were stable under the 2 wet-dry cycles. With the increase in initial water content, the sensitivity of wet-dry cycles to the compression deformation, structural parameter, and water retention gradually decreased. The sensitivity of initial water content to the compression deformation, structural parameter, and water retention gradually reduced with the increasing wet-dry cycles. Moreover, the influence mechanism of wet-dry cycles and initial water content on the macro-parameters and structure was mainly weakening the particle cementation strength. With the increase in initial water content, the decreasing range of the inter-aggregate cementation strength and intra-aggregate cementation strength under the influence of wet-dry cycles decreased. With the increase in wet-dry cycles, the decreasing range of the inter-aggregate cementation strength and intra-aggregate cementation strength under the influence of initial water content decreased.

Effect of wetting-drying cycles on the Cu bioavailability in the paddy soil amended with CuO nanoparticles

The extensive application of metal-based nanoparticles can pose environmental risks, but how the alternation of wet and dry caused by natural precipitation and artificial irrigation affects the environmental fate of nanoparticles is still unclear. Here, we investigated the underlying mechanisms of wetting-drying cycles (WDCs) on the Cu bioavailability in paddy soil treated with CuO nanoparticles (100 and 500 mg/kg) during 140 days by comparing with drought and flooding conditions. The results show that soil moisture content greatly affected the soil pH and redox potential. The bioavailable Cu contents in the WDCs exposed to CuO nanoparticles were positively correlated to moisture content and WDCs number. The fit result of the pseudo-second-order equation indicates that WDCs greatly prevented the aging process of Cu in soil. Furthermore, WDCs transformed oxidizable Cu to water-soluble, acid extractable and reducible Cu. WDCs markedly promoted the degradation of dissolved organic matter and the transformation of acid-soluble sulfate to water-soluble inorganic sulfate, meanwhile, significantly enhanced the contents of crystalline iron oxides by 22–57% and 82–326% with respect to drought and flooding, but reduced the level of ferrous iron by 37–67% compared to the flooding. µ-XRF analysis shows that the fate of CuO nanoparticles might be mainly determined by Fe under WDCs condition but by S in flooded soil. This study can provide a comprehensive assessment on the impact of natural precipitation and artificial irrigation on the environmental risks of MNPs.

Long-Term Effect of Wetting-Drying Cycles on the Bioavailability of Cuo Nanoparticles in the Paddy Soil

Long-Term Effect of Wetting-Drying Cycles on the Bioavailability of Cuo Nanoparticles in the Paddy Soil

Effect of Wet-Dry Cycles on the Bond Behavior of Fiber-Reinforced Inorganic-Matrix Systems Bonded to Masonry Substrates.

In recent years, inorganic-matrix reinforcement systems, such as fiber-reinforced cementitious matrix (FRCM), composite-reinforced mortars (CRM), and steel-reinforced grout (SRG), have been increasingly used to retrofit and strengthen existing masonry and concrete structures. Despite their good short-term properties, limited information is available on their long-term behavior. In this paper, the long-term bond behavior of some FRCM, CRM, and SRG systems bonded to masonry substrates is investigated. Namely, the results of single-lap direct shear tests of FRCM-, CRM-, and SRG-masonry joints subjected to wet-dry cycles are provided and discussed. First, FRCM composites comprising carbon, polyparaphenylene benzobisoxazole (PBO), and alkali-resistant (AR) glass textiles embedded within cement-based matrices, are considered. Then, CRM and SRG systems made of an AR glass composite grid embedded with natural hydraulic lime (NHL) and of unidirectional steel cords embedded within the same lime matrix, respectively, are studied. For each type of composite, six specimens are exposed to 50 wet–dry cycles prior to testing. The results are compared with those of nominally equal unconditioned specimens previously tested by the authors. This comparison shows a shifting of the failure mode for some composites from debonding at the matrix–fiber interface to debonding at the matrix-substrate interface. Furthermore, the average peak stress of all systems decreases except for the carbon FRCM and the CRM, for which it remains unaltered or increases.

Effect of wet-dry cycles on standard & polymer-amended GCLs in covers subjected to flow over the GCL

The performance of five different GCLs (two GCLs with standard sodium bentonite and three GCLs with polymer enhanced bentonite) subjected to three different climatic modes of wet-dry cycles simulating conditions to which a GCL might expose in cover systems over a prolonged time is reported. The wetting cycles lasted for 8 h, while the drying cycles varied between 16 h, seven days, and 14 days. It is shown that after around a year of accelerated aging, the hydraulic conductivity of the aged GCLs increased notably when permeated with tap water at an applied effective stress of 15 kPa for a range of heads (0.07, 0.14, 0.21, 0.49, and 1.2 m). The combined effects of the number and the duration of the wet-dry cycles, the GCL's mass per unit area, the carrier geotextile, the size and the number of the needle punch bundles, and the thermal treatment to bond the needle-punch bundles to the carrier geotextile are discussed. The poor hydraulic performance of the polymer-amended/modified bentonite GCLs is discussed.

Effect of wet-dry cycles on shear strength of residual soil

In order to investigate the relationship between the shear strength of residual soil and the number of repeated wet-dry cycles it underwent, the direct shear for different water content, different numbers of wet-dry cycles and different vertical stresses were examined. Based on the comprehensive structural potential theory, a comprehensive structural potential model considering the water content, the number of wet-dry cycles and the vertical stress was constructed. Then, the internal relationship between microstructure characteristics and structural strength attenuation of residual soil under alternate wet-dry conditions was emphatically discussed. As the number of wet-dry cycles and water content increased, the structural variability provided by the soil particle arrangement increased, while the structural stability provided by the soil particle cohesion decreased, causing the shear strength and structural potential of the soil to show a downward trend. As vertical stress increased, the variation range of structural stability was greater than that of structural variability. This asynchronous change caused decreased soil structural potential mτ. Under the same levels of vertical stress and the same water content, the model we constructed well represented the exponentially decreasing trend between the structural potential and the increased number of wet-dry cycles. Scanning electron microscope (SEM) images of the sample after five wet-dry cycles showed that the surface layer had lifted and the overhead structure between aggregates was clear, suggesting that unit cell connections had changed from face-to-face contact to edge-to-surface contact. That is, the overall orientation of the unit cell was diminished. As the successive wet-dry progressed, the overhead structure provided a more open water migration channel. The nuclear magnetic resonance (NMR) test showed that the content of micropores in soil samples decreased, and the proportion of mesopores and macropores increased, resulting in a decrease in soil strength. With the further development of wet-dry cycles (>5), the peak and residual strength of the soil gradually decreased to be stable. This is related to the decrease in soil saturation after multiple wet-dry cycles, and the stronger the stabilizing effect provided by soil–water meniscus.

Effect of Wetting-Drying Cycles on Desiccation Crack Pattern and Soil Behavior

Cracking, shrinkage, and curling of soils, in general, take place due to drying. These deformations lead to many problems include the development of main paths for water flow and pollutant transport, reduction of soil strength (and impact on other mechanical properties of soils), erosion in slopes, landslides, increase infiltration capacity of the soil and the differential settlement problems. Few studies have investigated the effect of wetting-drying (W-D) cycles on desiccation cracks of soils. The effect of multiple wetting-drying cycles in the cracking behavior was investigated in this research by performing several wetting-drying (W-D) cycles on the initially saturated samples (of pure kaolinite and a mixture of kaolinite with bentonite) under the lab atmosphere (24 ± 1 °C, and 52 ± 2% of RH). The weight of each sample was monitored using a computerized scale (with an accuracy of 0.01 g) connected to the computer. During the test, the water evaporation path with the development of surface cracks and volume shrinkage was monitored by means of digital images. It was observed that the crack patterns changed during the initial cycles, but there was an equilibrium state in the third and fourth W-D cycles. Additionally, it was observed that the main cracks formed in the first dry path were virtually closed after 10 minutes of the second wetting path; in the meantime, small cracks (fissures) were initiated after this wetting process. It was, also, detected that soils with high plasticity required more W-D cycles to reach the equilibrium condition than soils with low plasticity. The results of these experiments are useful for understanding the effect of different seasons on soil behavior.

Effects of wetting-drying cycles and desiccation cracks on mechanical behavior of an unsaturated soil

The effects of wetting-drying (W-D) cycles on the desiccation-induced cracking of a fat clay (CH) as well as the role of soil suction in the evolution of soil strength, were investigated. Cylindrical block soil samples (50 mm in diameter and 100 mm in height) compacted to a dry density of 1.3 Mg/m3, were subjected to 3 stages of drying at a temperature of 22 ± 2 °C, the first of which had an initial water content of 25%. Three parallel samples were retrieved and tested for unconfined compressive strength (UCS) and surface fracture characteristics at moisture content levels ranging from 13% to 25%. Analyses of images of crack patterns obtained using stereological software, indicate that the pattern of increases in UCS with decreasing moisture content induced by drying, is strongly affected by the intensity of cracks on the samples. Desiccation cracking only occurred in the 2nd and 3rd stages of soil drying. During the first stage of drying, the stress-strain curve of the soil exhibited increase in slope with decreasing water content. This implies the domination of suction at the initial stages. The number of crack segments observed on samples, increases with W-D cycles, thus decreasing soil brittleness. However, increase in W-D cycles does not significantly affect the soil water retention characteristics. These findings illustrate the significant role played by soil suction in strengthening soils against the degradation effects of cracks during the early stages of drying. As drying proceeds, the proliferation of cracks eventually reduces soil strength as soil suction is overcome. Therefore, in developing structures on clayey soils that will be subjected to seasonal changes in moisture content, assessments of the balance of the effects of suction and soil desiccation cracking should be made.

Effect of wet-dry cycles on disintegration characteristics of clay-bearing sandstone with UF cracks

UF cracks in rock masses commonly occur due to the unloading effect, which constantly happens after the variation of in-situ stress field or rock excavation. When undergoing periodic water fluctuation, rock mass with UF cracks is vulnerable to deterioration or even disintegration, especially for clay-bearing sandstone. To study the effect of changes in moisture on rock samples with UF cracks, clay-bearing sandstone from the Triassic Badong group in the Three Gorges Reservoir Area were chosen and investigated. The rock samples with UF cracks are obtained by conducting triaxial unloading confining pressure experiment. The effect of wet-dry cycles on the morphology properties and microstructure of the UF surface was investigated. The characteristics of particle-size uniformity from the sieve test were obtained by the calculation of RMS of particle contents. The test results show that UF cracks widen significantly and the disintegrated mass increases rapidly in the first three wet-dry cycles, while the fractal dimension of UF surface decreases sharply, but afterwards the disintegrated mass changes gently and the UF surface tends to be flat and smooth. Then, the RMS calculation of particle contents quantitatively evaluate the clay-bearing sandstone’s disintegration properties, which indicate the particle uniformity plays a key role on its disintegration mechanism. During wet-dry cycles, the tested samples tend to disintegrate more rapidly and entirely with the decrease of particle uniformity.

The effect of wet-dry cycles on tensile properties of unidirectional flax fiber reinforced polymers

The impact of moisture is a critical research focus for natural fibres. There is a significant decrease in mechanical performance when fully saturated; however, this may not be representative of real-life applications. In this study, the tensile performance of flax fibre reinforced polymers (FFRP) is investigated when exposed to wet-dry cycles. Manufacturing method, fibre type and resin type were varied throughout this research program. Vacuum bag moulded specimens exhibited an increased strength of 19%, increased rupture strain of 105% and reduced tensile modulus of 29% when saturated; however, it reverted to its original state once dried. When exposed to wet-dry cycles, a statistically-significant reduction in mechanical properties began after 3 cycles, with a maximum reduction of 12% strength and 19% stiffness. Conversely, degradation for wet lay-up moulded specimens was delayed until 12 cycles. When epoxy was replaced with an epoxidized pine oil (EPO) blended resin, there was no mechanical difference throughout wet-dry cycles; however, FTIR showed signs of hydrolysis for both resins. Furthermore, the glass transition temperature of epoxy reduced from 87.2° to 77.8 °C, whereas that of EPO increased from 65.6 °C to 70.2 °C. Glass-FRP was tested in parallel, and exhibited no change to performance across the entire conditioning protocol.

Potassium fixation capacity of some highly calcareous soils as a function of clay minerals and alternately wetting-drying

ABSTRACTThe current research was done to investigate the effect of wetting-drying cycles, time, and clay mineralogy on K fixation capacity of highly calcareous soils. In order to conduct the study, eight soil samples were collected. The samples were treated with different concentrations of K including 200 (K1), 400 (K2) and 800 mg kg−1 (K3) and 8 different incubation time including 6 h (t1), 24 h (t2), 72 h (t3), one week (t4), two weeks (t5), one month (t6), two months (t7) and three months (t8). Also, a wetting-drying treatment was done (td) in order to simulate the effect of irrigation and soil drying on K fixation. The results showed that for all K levels addition, the percentage of fixed K was increased with time. The K fixation content was increased with the increase in the added K from K1 to K3, while K fixation percentage was decreased. The results also showed that there was a significant difference between soils with wetting-drying treatment (td) and soils with three-month incubation (t8) in K fixation capacity, so that the fixation of K by the soils was increased with wetting-drying cycles.

Strength and durability characteristic of alkali activated GGBS stabilized red mud as geo-material

Abstract Red mud (bauxite residue) is generated during the Bayer’s process of aluminium production in the ratio of one part aluminium to 0.8–1.5 part red mud and is considered as an industrial waste. The storage of unutilised red mud creates a geoenvironmental problem due to its highly alkaline nature (pH > 11) as it contaminates the groundwater as well as surface water. The present paper discusses the strength and durability properties of the stabilized red mud using alkali (Na2SiO3) activated ground granulated blast furnace slag (GGBS) and its microstructural property for possible application as a geo-material. One of the major problems associated with the geo-materials is the strength loss and weathering due to the exposure to adverse environment. So, the emphasis has been given to the durability of the stabilized red mud by keeping in mind its various uses in geotechnical construction. The durability studies are performed by considering the effect of wet-dry cycles on compressive strength. In addition, the results of slake durability test and impact strength index are also discussed. The microstructural and chemical investigations are performed using scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively, to correlate with the strength and durability characteristics. The chemistry of leachate in terms of heavy toxic metals (Hg, As, Pb, and Cr) as identified by EPA is also studied and it was found that the stabilized red mud is non-toxic.

Strength and Deformation of Unsaturated Compacted Clay under Wetting-Drying Cycles

Strength and deformation of unsaturated compacted clay under wetting-drying cycles considering different amplitudes and numbers have been studied in the present study. A non-suction controlled method was applied to carry out cyclic wetting-drying on the compacted clay, and the effect of wetting-drying cycles on confined compressive strength peak and deformation of specimens have been investigated. The results show that wetting-drying cycles can reduce the strength of compacted clay, and after 4-5 times of cycle the strength tends to be stable. The height and volume of compacted clay increase as the number of cycle increases. It can be indicated that under wet condition the influence of amplitude of wetting- drying cycle on the deformation is greater than that under dry condition.