การไหลของน้ำในดินเนื่องจากอิทธิพลของน้ำฝน

Landslides triggered by rainfall are widely known disaster related to the interactions between hydrological responses and change in strength of the sloping ground. The infiltration of rainwater into the soil results in increment of soil water content, hence the drop of shear strength and factor of safety against slope failure. Understanding this interaction is vital to enhance the landslides warning system such that mitigation of landslide disaster can be performed effectively. This research investigated the seepage response in the soil by one-dimensional infiltration model under 3 rainfall conditions : 1) Rainfall intensity was less than permeability coefficient of the soil, 2) Rainfall intensity was close to permeability coefficient of the soil, and 3) Rainfall intensity was higher than permeability coefficient of the soil. Soil samples used in this study were gathered from the landslide warning station ; Ban Khlong Sathon, Wang Mi Sub-district, Wang Nam Khieo District, Nakhon Ratchasima Province. The test found that, under the 1st rainfall condition, the change of soil volumetric water content can be divided into two phases : infiltration phase and rising of water table phase. The infiltration phase involved the downward movement of the wetting front. In this phase, the water content increased from the initial value of the volumetric water content ( wi ) to the final volumetric water content called volumetric water content behind wetting front ( wb ) to reach saturated water content ( sat ). When the wetting front reaches to the impervious layer, the water content in the soil will increase due to the rising of water table. The magnitude of wb increases with increasing the magnitude of rainfall intensity. The magnitude of wb is equal to sat when the rainfall intensity is equal to the permeability coefficient of the soil. In addition, the results showed that the wetting front velocity also depends on the rainfall intensity

อิทธิพลของคุณสมบัติเชิงชลศาสตร์ในดินถมและวัสดุระบายน้ำใยสังเคราะห์ต่อการระบายน้ำในกำแพงกันดินเสริมกำลัง

This research aims to investigate the effect of water retention characteristic of the soil and drainage material (geocomposite) on seepage responses in mechanical stabilized earth walls by using geocomposite as drainage system. A set of experiments on physical models was conducted such that the data set obtained from the tests were used to calibrate the numerical models. The well calibrated numerical models were then used to perform parametric study. The studied parameters were van Genuchten parameters (ga, gn, Sres, Ssat) and coefficient of permeability (k) of the relevant materials. Results from the parametric study show that the water retention characteristic of the soil outside the reinforced zone plays no role to the hydraulic response of the soil inside the reinforced zone. However, the coefficient of permeability of the soil outside the reinforced zone plays important role to the level of the phreatic surface inside the reinforced zone. Hence, the coefficient of permeability of the soil outside the reinforced zone must be taken into account when designing drainage system

คุณสมบัติทางกลของวัสดุจีโอโพลิเมอร์คอมโพสิตเสริมเส้นใยปอ

This paper describes the physical and mechanical properties of geopolymer composite reinforced with kenaf fiber (1, 3, and 5 wt.%). Kenaf fiber was surface treated using sodium hydroxide 2M with 24 hours prior to mixing process. Test results showed that density, porosity and water absorption of geopolymer composites mixed with surface-treated kenaf fiber and those mixed with surface-untreated kenaf fiber are almost identical. Interfacial adhesion between fibers and matrix plays a critical role on mechanical performance of the natural fibers reinforced geopolymer composites. The degradation of reinforced fibers due to alkaline attack may result in existence of micro-crackes at the fiber and matrix interface. As surface treatment can diminish the alkaline sensitive component from the kenaf fiber and increase the surface roughness, the treated kenaf fiber geopolymer composite yields the mechanical properties better than the untreated kenaf fiber geopolymer composite does. Comparing with the geopolymer without fiber reinforcement, the flexural strength of the treated kenaf fiber geopolymer composites are 107%, 276% and 311% and that of untreated kenaf fiber geopolymer composites are 19%, 133%, 236% for 1%, 3% and 5% fiber, respectively

การเคลื่อนที่ของน้ำใต้ดินเค็มภายใต้กระบวนการคาพิวลารีในดินทรายและดินร่วนปนทรายจากพื้นที่ดินเค็ม จ.นครราชสีมา

This paper presents experimental results in laboratory based on the investigation of saline groundwater movement influenced by capillary force. Soil layer is simulated by compacting soil sample in transparent tube of diameter 10 cm and 100 cm height and set groundwater level of 85 cm below soil surface. The experimental studies are divided into 5 different cases: 1) Column I: Sand with deionized groundwater(DG) 2) Column II: Sand with saline groundwater(SG) 3) Column III: Sandy loam with DG 4) Column IV: Sandy loam with SG and 5) Column V: Sandy loam with SG and adding artificial sunlight to increase evaporation . The experimental results show that vertical movement rate and capillary pressure head between DG and SG for sand are similar. For sandy loam sampling from salinity – affected area in Nakhon Ratchasima, the results between DG and SG are explicitly different. SG gives high capillary pressure head, high moisture movement rate and high soil moisture content compare to DG at equal level of soil depth. The cause can be that sodium ion (Na+) brought by saline water and staying in the voids between soil grain can absorb more water content. For sandy loam, soil moisture is accumulated at the soil surface in high water content, compare to the other level of soil depth. If this saline moisture is evaporated by artificial radiation, salt’s crystallization will be found on the soil surface

เครื่องต้นแบบจำลองการเปลี่ยนความฝืดของผิวจราจรและระยะร่องล้อเนื่องจากอิทธิพลของจำนวนรอบวิ่ง

Literature reported that number of accidents was directly related to pavement skid resistance. Hence, a key element to enhance road safety is to maintain skid resistance of pavement. Due to no available machine to measure pavement skid resistance under cycles of wheel track, a prototype machine for measuring pavement skid resistance and rutting under various simulated cycles of wheel track was developed This prototype machine is flexible for future modification; i.e., various factors relating to traffic load such as wheel track cycle, and wheel track load can be adjusted using a software. Results of cyclic skid and rutting tests on an asphaltic pavement specimen show that rutting and rapid deterioration in pavement skid resistance are found at first 1000 cycles of wheel track. The rate of deterioration decreases with increasing wheel track cycle

Exploring the effects of geotextiles in the performance of highway filter drains for sustainable and resilient highway drainage

The authors would like to thank Carnell Support Services Ltd for funding the study. Luis A. Sañudo-Fontaneda also wish to thank the funding for the development of the UOStormwater Engineering Research Team by the University of Oviedo through the research project with reference PAPI-17-PEMERG-22

พื้นผิวครากสำหรับดินไม่อิ่มตัวด้วยน้ำ

This paper presents yield surface of unsaturated soils on a net stress - suction plane. A proposed model was developed based on a combination of soil structure and elasto-plastic theory. The soil structure is employed to establish an initial yield surface. The soil structure is normally represented via the soil water characteristics curve (SWCC). Hence, the initial yield surface could be derived by mathematic manipulating with the SWCC. A subsequence yield surface was derived by equality of plastic volumetric strain between two stress paths traveling along the same yield surfaces. For a given yield surface, yield stresses provided from the derived yield surface remain constant if a soil suction does not reach an air entry suction. Once, the soil suction develops beyond the air entry suction, the magnitude of yield stress increases with suction

Strength and compressibility of lightweight cemented clays

Lightweight cemented clays have wide applications in infrastructure rehabilitation and in construction of new facilities. The strength and compression characteristics of lightweight cemented clays with non- to high swelling potential are investigated and presented in this article. The workable state, the optimum water content to produce the lightweight cemented clay, is about 1.9 times the liquid limit. The void/cement ratio, V/C, which is defined as the ratio of the void volume of clay to the cement volume, is proved to be the prime parameter governing the strength and compression characteristics of lightweight cemented clays. The fabric (arrangement of clay particles, clusters and pore spaces) reflected from both air foam content and water content is taken into consideration by the void volume while the inter-particle forces (levels of cementation bond) are governed by the input of cement (cement volume). A strength equation in terms of V/C at a particular curing time is introduced using Abram\u27s law as a basis. From the critical analysis of test results, a mix design method to attain the target strength and unit weight is suggested. This method is useful for both engineering and economic viewpoints. (C) 2012 Elsevier B.V. All rights reserved

Strength of sustainable non-bearing masonry units manufactured from calcium carbide residue and fly ash

This paper aims to study the viability of using Calcium Carbide Residue (CCR) and fly ash (FA) as a cementing agent (binder) for the manufacture of non-bearing masonry units without Portland Cement (PC). CCR and FA are waste products from acetylene gas factories and power plants, respectively. The test samples were made up at a binder to stone dust ratio of 1:8 by weight. The studied water to binder (W/B) ratios were 0.50, 0.75 and 1.00, and the CCR/FA ratios were 80:20, 60:40 and 40:60. The W/B ratio of 0.75 and CCR/FA ratio of 40:60 were found to be an optimal mix proportion providing the highest both unit weight and strength. The higher CCR/FA ratios provide lower strength values because the silica and alumina in FA are insufficient to react with abundant Ca(OH)2 in the CCR for the pozzolanic reaction. The optimal mix proportion provides the strength of the CCR-FA based material greater than 20 MPa, which is acceptable for non-bearing masonry unit. The cost analysis showed that the material costs of the CCR- FA masonry unit were 40% lower than those of the PC masonry unit. Besides the cost effectiveness, the outcome of this research would divert significant quantity of CCR from landfills and considerably reduce carbon emissions due to PC production