Tree water uptake on suction distribution in unsaturated tropical residual soil slope

This study provides an investigation of active root tree zone located at the toe of a slope. This section and its vicinity generated matric suction due to tree water uptake on tropical residual soil slope. The research employed several approaches i.e field monitoring, laboratory experimental and numerical modelling. A field monitoring was carried out to collect matric suction data at the slope with two conditions; in absence of a tree and with a tree located at the toe of a slope. The unsaturated shear strength behaviour of soil under different stress level is investigated, using uncomplicated testing procedure subject to actual matric suction encountered during field monitoring. The numerical simulation modelling was applied based on the laboratory results to obtain the most appropriate condition to replicate the tree water uptake within the soil slope. A decrease in matric suction occured after a long duration of intense rainfall. This condition was function as an initial condition before the water uptake driven by active root tree generated to the maximum matric suction (low moisture content). The pattern of matric suction profiles revealed that majority of matric suction changes was greater at the proximity of tree trunk below 4 m and at a shallow depth of 0.5 m. Transpiration on single mature tree has significantly altered the matric suction or moisture variation distribution on an unsaturated soil slope. This study also illustrated the nonlinear relationship between the apparent shear strength and suction influencing the stability of the slope. The assessment of slope stability due to the influence of a tree induced suction was provided in this research. The factor of safety against slope failure has improved up to 63 % on slope with tree at toe compared to a slope without tree. Lastly, the numerical simulation modelling of matric suction induced by a tree has been verified through comparison to actual field monitoring results recorded during the dry period. Generally, an acceptable aggrement between simulation and field monitoring results has been achieved. This research delivers a strong belief that a preserved mature tree can improve soil properties in slopes designs

The Application of Unmanned Aerial Vehicle (UAV) For Slope Mapping at Gambang Damai Residents, Pahang: A Case Study

In this paper, the work of slope mapping using unmanned aerial vehicle (UAV) with its perimeter, area and volume of certain selected areas at Perumahan Taman Gambang Damai in Kuantan Pahang are discussed. Previous work of slope mapping using traditional survey equipment considered as time consuming and very challenging especially in hilly regions. This study also focused on determining the potential slope hazard based on slope angle. Modern UAV able to take high quality image which essential for the effectiveness and nature of normal mapping output such as Digital Elevation Model (DEM) and Digital Orthophoto. These photos captured by the UAV will later exported to Agisoft to generate full map of study area. With the help of Global Mapper, the measurement such as perimeter, area and volume of selected study areas can be determined easily and considered as the main interest in this study. Based on the results of the two slopes (slope A and slope B), slope B give a bigger volume which is 1469.7 m3 compare to slope A which is 1382.9 m3. The enclosed area for slope A is 1634.3 m2 which is bigger compare to slope B which is 766.86 m2. Besides, the perimeter of slope A is 162.28 m which is bigger compare to slope B which is 159.45 m. In addition, another outcome of this study is, this modern method of mapping helps researchers and engineers to study the possibility of slope hazard based on their respective slope angle. From the results, the angle for slope A is 47.35⁰ while the angle for slope B is 54.75⁰. Both of the slopes considered as very steep slope. In conclusion, modern technology of UAV proves to be very effective for mapping in geotechnical engineering. Slope mapping using multi-rotor UAV help researchers and engineers to obtain slope measurement within short period of time compare to previous traditional method

The Application of Unmanned Aerial Vehicle (UAV) For Slope Mapping at Gambang Damai Residents, Pahang: A Case Study

In this paper, the work of slope mapping using unmanned aerial vehicle (UAV) with its perimeter, area and volume of certain selected areas at Perumahan Taman Gambang Damai in Kuantan Pahang are discussed. Previous work of slope mapping using traditional survey equipment considered as time consuming and very challenging especially in hilly regions. This study also focused on determining the potential slope hazard based on slope angle. Modern UAV able to take high quality image which essential for the effectiveness and nature of normal mapping output such as Digital Elevation Model (DEM) and Digital Orthophoto. These photos captured by the UAV will later exported to Agisoft to generate full map of study area. With the help of Global Mapper, the measurement such as perimeter, area and volume of selected study areas can be determined easily and considered as the main interest in this study. Based on the results of the two slopes (slope A and slope B), slope B give a bigger volume which is 1469.7 m3 compare to slope A which is 1382.9 m3. The enclosed area for slope A is 1634.3 m2 which is bigger compare to slope B which is 766.86 m2. Besides, the perimeter of slope A is 162.28 m which is bigger compare to slope B which is 159.45 m. In addition, another outcome of this study is, this modern method of mapping helps researchers and engineers to study the possibility of slope hazard based on their respective slope angle. From the results, the angle for slope A is 47.35⁰ while the angle for slope B is 54.75⁰. Both of the slopes considered as very steep slope. In conclusion, modern technology of UAV proves to be very effective for mapping in geotechnical engineering. Slope mapping using multi-rotor UAV help researchers and engineers to obtain slope measurement within short period of time compare to previous traditional method

Tree Water Uptake and Suction Distribution on Tropical Residual Soil Slope

This paper present an exploration of soil matric suction effected by water uptake via tree root at toe of slope on various condition between wet condition (high rainfall) and dry condition (prolonged no rainfall). Matric suction generated by active root tree has substantial influence soil moisture content on residual soil slope. A field monitoring was carried out to collect matric suction data at slope in two conditions; with a tree located at toe of slope and absent of a tree. The installations of instruments particularly at slope with tree at toe were placed within vicinity of the tree with certain depths and distances. The matric suction data from field monitoring was influence by the rainfall events that lead to the instability of soils slope. Analysis of soil matric suction distribution pattern indicates that the highest matric suction value was at shallower depth and proximity of tree. The matric suction profiles obtained from field monitoring are applied as an input data to develop soil matric suction contour. The effect of transpiration driven by active root zone generated matric suction on soil at vicinity of tree may create dry soil to increase soil shear strength

Forensic assessment on landfills leachate through electrical resistivity imaging at Simpang Renggam in Johor, Malaysia

From years to years, the usage of electrical resistivity imaging (ERI) method dominated by geophysicist has increased tremendously in geotechnical engineering application owing to the efficiency and effectiveness of the method in term of time, cost and also data coverage. The forensic assessment performed with respect to the particular reference to ERI in assessing the landfills leachate at Simpang Renggam, Malaysia. There were two lines of ERI performed at the study area by using ABEM Terrameter LS 2 set of equipment based on Schlumberger array. Furthermore, the analysis made based on the electrical resistivity anomaly managed to detect the presence of chemical contaminants in the soil with particular reference to the chemicals resistivity values which was associated to low resistivity anomaly. Besides, the heterogeneous of the subsurface material presented in the paper by using integrated ERI analysis enabled forensic assessment of the leachate. The leachate from the landfills was believed to occur owing to the failure of the systems in accommodating and treating the waste which became worst with the present of heavy rainfall. In retrospect, the ERI result was applicable to be adopted in detecting the leachate and thus can assist the authority in taking immediate measure to prevent the frequent water disruptions at the study area

Tree induced suction on slope stabilization analysis

This research explores the effect of active root zone related to slope stabilization. The matric suction produced by mature tree was determined with high and moderated intensity of rainfall event condition. The increasing of soil moisture and pour water pressure can significantly reduce shear strength of soil, which leads to shallow slope failure. This exploration is concentrate at active root zone of the tree at toe of the slope. The effect only focused on hydrological aspect with soil suction pattern within vicinity of the tree. The monitoring result show a substantially increase in soil suction at slope with tree at toe. The effect of tree water uptake on soil suction distribution is applied for slope stability analysis that significantly changes stability of the slope. The rainfall events also lead to variation on soil suction and factor of safety of the slope. The influence of water uptake from root activity at the toe of slope created a dry condition and substantially increased the factor of safety against slope failure up to 63

The Application of Unmanned Aerial Vehicles (UAV) for Slope Mapping with the Determination of Potential Slope Hazards

In our modern world, the application of small unmanned aerial vehicles (UAV) for monitoring work or slope mapping expanded and is widely used by people in the construction field and researchers. Slope mapping can be considered challenging when using traditional surveying methods since most slopes especially in forest regions are high and considered risky if monitored by human themselves. Other than that, mapping by using UAV need a lower number of manpower to operate the device itself which is more than enough to be conducted by a single person only. This paper discusses the applications of unmanned aerial vehicles for mapping and also its important parameters including perimeter, area and also volume of certain selected area. With the development of modern technology, the utilization of UAV to gather data for geological mapping is becoming easier as it is quick, reliable, precise, cost-effective and also easy to operate. High imagery quality and high-resolution images are essential for the effectiveness and nature of normal mapping output such as digital elevation model (DEM) and also orthoimages. With the help of established software, the parameters of three selected study areas (stockpile, slope A and slope B) can be determined easily which can be considered as one of the main interest in this study. In addition to that, the horizontal and vertical cross section of every selected area can be obtained which help to determine the highest and lowest point of each area. From this cross section, the slope path profile can be determined. Other than that, from this path profile, the potential slope hazard will be determined based on the slope angle (slope classes) as suggested by the United States Department of Agriculture (USDA). Overall, the application of unmanned aerial vehicles for photogrammetry together with slope mapping and slope hazard monitoring can be considered as a reliable modern technology which ease the work with proper assurance of analysis due to its advancement and powerful technology. This modern surveying device helps workers and researchers to simplify and fasten their work

The effectiveness of unmanned aerial vehicle (UAV) for digital slope mapping

This paper discusses the applications of unmanned aerial vehicle (UAV) for slope mapping and its important parameters including perimeter, area and volume of certain selected areas. Modern UAV able to take high quality image which essential for the effectiveness and nature of normal mapping output such as Digital Surface Model (DSM) and Digital Orthophoto. This photo captured by UAV will later transfer to commercial software to generate full map of study area. Three locations in Kuantan Pahang are chosen (Sungai Lembing, Politeknik Sultan Ahmad Shah ‘POLISAS’ and Pahang Matriculation College) for slope mapping. With the help of established software, the measurement (perimeter, area and volume) of selected study areas can be determined easily and considered as the main interest in this study. In addition, another outcome of this study is, this modern method of mapping will be compare to traditional method of mapping which proven to be more effective in term of low costing, low time consuming, can gather huge amount of data within short period of time, low man power needed and almost no potential risk of hazardous effect to man. In conclusion, modern technology of UAV proves to be very effective for mapping in geotechnical engineering. Slope mapping help researchers and engineers to obtain slope measurement within short period of time compare to previous traditional method

Time-lapse resistivity investigation of salinity changes at an ex-promontory land: a case study of Carey Island, Selangor, Malaysia

Time-lapse resistivity measurements and groundwater geochemistry were used to study salinity effect on groundwater aquifer at the ex-promontory-land of Carey Island in Malaysia. Resistivity was measured by ABEM Terrameter SAS4000 and ES10-64 electrode selector. Re�lationship between earth resistivity and total dissolved solids (TDS) was derived, and with re�sistivity images, used to identify water types: fresh (ρe > 6.5 � m), brackish (3 � m < ρe < 6.5 � m), or saline (ρe < 3 � m). Long-term monitoring of the studied area’s groundwater quality via measurements of its time-lapse resistivity showed salinity changes in the island’s groundwater aquifers not conforming to seawater-freshwater hydraulic gradient. In some aquifers far from the coast, saline water was dominant, while in some others, freshwater 30 m thick showed ground�water potential. Land transformation is believed to have changed the island’s hydrogeology, which receives saltwater pressure all the time, limiting freshwater recharge to the groundwater system. The time-lapse resistivity measurements showed active salinity changes at resistivity-image bottom moving up the image for two seasons’ (wet and dry) conditions. The salinity changes are believed to have been caused by incremental tide passing through highly porous material in the active-salinity-change area. The study’s results were used to plan a strategy for sustainable groundwater exploration of the island

Rainfall induced residual soil slope instability: building cracked and slope failure

Rainfall is one of the factors of slope failures due to the intensity of rainfall that will seep and increase the moisture content of geo-materials. One of the important role in slope stability is matric suction. This study present the relationship between rainfall and suction of soil which induced the slope instability and the slope stability analysis involving a building which may cause by instability due to suction variation. The slope had separated into three parts which are top of slope, middle of slope and toe of slope. Every part has been inserted with three tensiometer with 0.3 m, 0.45 m and 0.9 m depth. Suction of soil on slope was carried out by using tensiometer. Intensity of rainfall was collected by using rain gauge which placed at open area which to compare with matric suction of soil. Several site and laboratory tests were carried out to identify the soil properties. Stability of slope was analyzed using Slope/w and Manual Calculation via input parameters collected from laboratory test and field test. Fellenius’ method was used to interpret the factor of safety for slope study. This includes the analysis of the factor of safety of slices at the selected area with its matric suction value. It was found that when the rainfall increased, the suction of soil decreased and affected to decrease of factor of safety. Hence, the constructed slope was suggested to be redesign to improve its safety factor