Geotechnical Model Research Articles

Energy dissipation of rammed earth-timber joints under cyclic loading

Rammed earth-timber joints without enlarged ends have been used in rammed earth buildings for several hundreds of years. Due to the embedment nature, the joint has a certain degree of flexibility, allowing the floor and roof beams to slide without damaging the rammed earth, enabling dissipating energy during earthquakes. The energy dissipation mechanism of rammed earth-timber joint has not yet been fully understood. This study studied the energy dissipation characteristic of eight rammed earth-timber joint specimens via cyclic pull-out/push-in experiments, investigating the effects of compressive loading, embedment length, and surface roughness on joint performance. Results show that the joint stiffness under cyclic loading was reduced nonlinearly with the increase of pull-out displacement until the occurrence of slippage. The high vertical compression from the upper level, the deformability of timber frames, and the plasticity of rammed earth were found to be the primary energy dissipators. A linear frictional and nonlinear geotechnical hysteretic model, combining frictional and soil mechanics theories, was established to represent the joint behavior. In addition, a simplified multi-linear hysteretic model was developed for the same purpose. The predictions and the measurements had good agreement, suggesting that geotechnical methods should be employed to analyze the joint, maintaining the assumption that both the timber frame and the rammed earth are linear-elastic.

Geotechnical parameters modelling and the radiation safety of expansive clayey soil treated with waste marble powder: a case study at west Gulf of Suez, Egypt

The present paper aims to reduce and detect the environmental impact of radioelement concentrations and waste marble powder (WMP) in the surrounding environment and additionally, improve the characteristics of the expansive soil and investigate the effect of stabilizers on the swelling soil to use a foundation layer. Different geotechnical laboratory tests have been performed on representative clay samples to define the physical and mechanical characteristics. The results indicate that the swelling pressure and swelling potential are reduced from (805.7 to 576 kN/m2) and (15.78 to 7.11%), respectively. The plasticity index decreased from 35.9% (high plasticity) to 19.4% (low plasticity), and the free swell index becomes zero by adding waste marble powder. Geospatial techniques have also been used to produce the distributions layers of different geotechnical characteristics and radioelements’ concentrations. These layers were integrated to produce a geospatial model. This model showed a noticeable improvement in the properties of clayey soils after the use of waste marble powder, which ranged from low expansion to high expansion. The radioelement concentrations of all samples are below an acceptable limit, except that the concentration of 40K is greater than the acceptable limit. This study recommends a 40% replacement of WMP. This amount is suitable and economical for this kind of treatment because of its positive solutions to protect the environment from pollution and reduce the cost of construction.

Analysis of earth pressure distribution on deep circular shafts in composite geological strata using centrifuge modelling

With the rapid development of urban underground space, the depth of working shaft has been gradually becoming deeper to accommodate the underground construction needs. The existing studies for earth pressure distribution of shafts are mainly focused on sandy soils within 30 m. There is a strong need to investigate the earth pressure distribution on deep shafts (more than 30 m) in complicated soil conditions using centrifuge modelling to fill the knowledge gap and provide experimental basis for design. In this paper, geotechnical centrifuge modelling was used to investigate the earth pressure distribution along deep circular shaft structures (with a depth of 100 m) in composite geological strata. Three centrifuge tests on model shafts in layered ground with different thickness of clay and sand were carried out, respectively. Drainage method was used in the experiment to simulate the unloading effect caused by excavation of soils inside the shaft model. The earth pressure distributions along the shaft lining before and after the excavation were investigated. The results were analysed and compared with other existing earth pressure theories. This research provides valuable insights for earth pressure distribution for design of circular deep shafts (e.g. 100 m) in composite geological strata.

PRELIMINARY STUDY ON PLASTICINE AS A SUBSTITUTE COHESIVE MATERIAL FOR GEOTECHNICAL PHYSICAL SOIL MODELING

<p>Plasticine is an artificial material made from solids such as gypsum, lime, mixed with petroleum jelly or micro wax and acid fat. The properties of plasticine are likely similar to natural clay and is influenced by oil content. The information about mechanical properties of plasticine is still very rare, and as such the study on it is riquired and must be conducted intensively. The preliminary laboratory study has been conducted to understand the behaviour of plasticines. Microwax and petroleum jelly based plasticines were utilised with the variation of oil content, whereas kaolin clay with the variation of water content is utilised as a reference material. The study is focusing on the stress-strain behaviour for both microwax and petroleum jelly based plasticines compared to the stress-strain behaviour of kaolin clay. This paper reports the result of preliminary investigation regarding the use of plasticine as an alternative artificial material for substitution of clay in soil modeling. Some engineering properties from unconfined compression strength (UCS) test and hand penetrometer are shown. The result indicates that the stress-strain behaviour of plasticine resembles the stress-strain behaviour of kaolin clay. The plasticine is suitable as a substitute cohesive material and it has a potential to be utilised for geotechnical material modelling in the future.</p>

PRELIMINARY STUDY ON PLASTICINE AS A SUBSTITUTE COHESIVE MATERIAL FOR GEOTECHNICAL PHYSICAL SOIL MODELING

Plasticine is an artificial material made from solids such as gypsum, lime, mixed with petroleum jelly or micro wax and acid fat. The properties of plasticine are likely similar to natural clay and is influenced by oil content. The information about mechanical properties of plasticine is still very rare, and as such the study on it is riquired and must be conducted intensively. The preliminary laboratory study has been conducted to understand the behaviour of plasticines. Microwax and petroleum jelly based plasticines were utilised with the variation of oil content, whereas kaolin clay with the variation of water content is utilised as a reference material. The study is focusing on the stress-strain behaviour for both microwax and petroleum jelly based plasticines compared to the stress-strain behaviour of kaolin clay. This paper reports the result of preliminary investigation regarding the use of plasticine as an alternative artificial material for substitution of clay in soil modeling. Some engineering properties from unconfined compression strength (UCS) test and hand penetrometer are shown. The result indicates that the stress-strain behaviour of plasticine resembles the stress-strain behaviour of kaolin clay. The plasticine is suitable as a substitute cohesive material and it has a potential to be utilised for geotechnical material modelling in the future.

Stability Analysis of a Landslide: A View with Implications of Microstructural Soil Characters

The 2015 Devrek landslide is one of the largest and most puzzling features on the Devrek-Eregli Highway in Zonguldak Province, in the north-west of Turkey. The landslide which was activated in March, was about 700 m long, 110 m wide with a volume of 1,100,000 m3. In order to assess the landslide hazard in a systematic way, we have employed several techniques such as geotechnical, microstructural and finite elements (FE) modelling. X-ray diffraction and X-ray fluorescence studies show low clay content in the crown section and the amounts of illite and sepiolite do not exceed 25% where there is detrital sand indicating that there is continuous sliding activity. The main sliding body demonstrates implications of liquefaction according to the amount of fine sand and clay obtained by laboratory measurements. The most active clay group prevailing the landslide formation are illite and sepiolite. Furthermore, rounded fine quarts have increased sliding and rolling activity risk according to their physical structures combined with high-seasonal rainfall rate. The FE method was used for both static and dynamic slope stability investigations. Since the landslide region are in a very active tectonic region, earthquake-triggered landsliding strongly correlates with measured peak ground acceleration. Therefore, we have tested the model in numerical dynamic analysis, and the results show a deterioration in landslide stability during seismic loading which puts the study area at risk. All analysis carried out for the landslide assessment shows a continued landslide hazard for the residential areas close to the landslide foot zone.

Geo-environmental monitoring and 3D finite elements stability analysis for site investigation of underground monuments. Horemheb tomb (KV57), Luxor, Egypt

The Valley of the Kings (KV) is a UNESCO world heritage site with more than thirty opened tombs. Since the first tombs were constructed, at least 24 historical flash flood events has been identified, each of which has been contributed to the destruction and deterioration of the tombs. Recently, most of these tombs have been damaged and inundated after 1994 flood. In order to understand the Geo-environmental impact mainly the past flash floods due to the intensive rainfall storm on the valley of kings and the long-term rock mass behavior under geostatic stresses in selected Horemheb tomb (KV57) and its impact on past failures and current stability, Remote sensing, GIS, LIDAR, 3D finite element stability analysis and rock mass quality assessments had been carried out using advanced methods and codes. Our work provides environmental satellite space views via landviewer Erath Observation System (EOS) Platform with passive and active sensors which include the Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), Atmospherically resistant vegetation index (ARVI), Green Chlorophyll Index (GCI), Normalized Burn Ratio (NBR), Normalized Difference Snow Index (NDSI), Light Detection And Ranging (LIDAR) images, Terrain (DEM) Digital Elevation Models, 3D geological maps. In other hand experimental and numerical geotechnical evaluations and modeling of the rock mass of these underground structures and their surroundings have been executed. We estimated the rock mass quality of the different members within the Thebes limestone and Esna shale formations using the mechanical testing and Rock Mass Rating (RMR), rock quality system (Q-system) and Geological Strength Index (GSI) systems. Our recent analyses show that the KV57 rock- cut tomb at Luxor has been cut into poor to very poor quality marl shale masses due to the impact of flash foods. Rock failures of ceilings and pillars were frequently facilitated by local, unfavorably oriented persistent discontinuities, such as tension cracks and faults. Other failures were related to the disintegration of the marl limestone and Esna shale Formations into individual nodules upon weathering. Our data suggest that, in ancient Egypt monumental tomb construction, low-strength rock masses rarely resulted in modifications of the planned tomb design in order to minimise the risk of rock falls and to prevent collapses. The current flood protection measures are not enough. For this two following measures are proposed 1—to rise the current wall by 50 cm. 2—to fill the depression by reshaping bathymetry.

BIM – AN APPLICATION IN GEOTECHNICAL ENGINEERING

BIM model represents a significant step forward within the frame of the overall process of construction. This new approach goes from the assumption that up to date praxis, which is represented by different sets of 2D or 3D drawings of drawings, technical reports and calculations does not cover all problems of the above mentioned overall process of construction. Basic principles of BIM will be discussed, not only from the view of 3D models of the structure design. The utilization of the BIM model during life time structure expectancy will be stressed - from the initial phase (investigation, design) via the phase of structure execution, maintenance and ending with structure demolition at the end of life time expectancy. Specificity of the geotechnical engineering is in this entire process fundamental, as each construction is in the interaction with ground. 3D model of the ground (geotechnical model) is therefore one of the basic individual parametric elements from which BIM model consist. Ground model is time dependant as geological profile and geotechnical properties are refinement during each phase of ground investigation as well during geotechnical structure construction. Final 3D Ground model together with 3D model of geotechnical structure represents a first significant step of the overall BIM model. In the case of underground or earth structures such output can be primordial element of the BIM model with parametric elements around it. Finally some other possibilities or practical applications are mentioned.

Centrifuge Modeling of Soft Soil Reinforced with Granular Columns

This paper presents a geotechnical centrifuge model of an embankment built in stages, over a 6.0 m layer of soft soil reinforced with nine floating granular columns arranged in a 3 × 3 square grid. The container was divided in two compartments where reinforced and unreinforced soil were tested simultaneously for comparison purposes. The load was applied by means of a 4 m high sand embankment (prototype dimensions) built in three steps. For each step, the centrifuge was stopped to allow the placement of the embankment layer and then re-accelerated up to 26 g and the excess of pore pressure was allowed to dissipate after each step. The instrumentation, comprised of total stress cells, pore pressure transducers and displacement transducers, was configured to collect information about the load transfer mechanism between the soil and the instrumented central column for each loading step during pore pressure dissipation. Results showed that despite representing only 30% of the total load, the first step provoked almost 70% of total vertical displacement. Finally, the columns were exhumed for a detailed and comprehensive visual analysis aiming to support and explain the results obtained.

Development of Data Integration and Sharing for Geotechnical Engineering Information Modeling Based on IFC

With the rapid development of infrastructure construction, geotechnical engineering has always been worthy of attention due to its complexity and diversity. Accelerating the informatization of geotechnical engineering will contribute to the project management, but the information contained in geotechnical engineering cannot be well integrated because of the lack of unified data standards. Building Information Modeling (BIM) has been considered as an effective technology to manage information, and Industry Foundation Classes (IFC) in BIM serves as a neutral and open standard for the exchange of information. However, it was found that BIM cannot express the information of some structure objects and geological objects well during the construction process of geotechnical engineering. Combined with the characteristics of geotechnical engineering, taking advantage of the good extensibility of IFC, this paper proposes a “Built‐In Generation Schema” for geotechnical structure models and a “Plug‐In Extension Schema” for three‐dimensional (3D) geological models, ultimately forming the basic data system of geotechnical engineering information models based on IFC. Applying extended IFC to the modeling process, the BIM‐based modeling method of geotechnical models is proposed. In addition, an IFC‐based platform is developed to integrate geological models and structure models for further displaying and analyzing of geotechnical engineering models. The work in this paper provides a feasible way and technical support for promoting the integration and sharing of geotechnical engineering information and enhancing the multiprofessional collaborative work.

Comparisons of Two Approaches for Geotechnical Model Calibration with Scarce Data

Geotechnical models are usually built upon assumptions and simplifications, inevitably resulting in discrepancies between model predictions and measurements. To enhance prediction accuracy, geotechnical models are typically calibrated against measurements by bringing in additional empirical or semiempirical correction terms. Different approaches have been used in the literature to determine the optimal values of empirical parameters in the correction terms. When measured data are abundant, calibration outcomes using different approaches can be expected to be practically the same. However, if measurements are scarce or limited, calibration outcomes could differ significantly, depending largely on the adopted calibration approach. In this study, we examine two most commonly used approaches for geotechnical model calibration in the literature, namely, (1) purely data‐catering (PDC) approach, and (2) root mean squared error (RMSE) method. Here, the purely data‐catering approach refers to selection of empirical parameter values that minimize coefficient of variation of model factor while maintains its mean value of one, based solely on measured data. A real case of calibrating the Federal Highway Administration (FHWA) simplified facing load model for design of soil nail walls is illustrated to thoroughly elaborate the differences in practical calibration and design outcomes using the two approaches under scarce data conditions.

ВЫДЕЛЕНИЕ КЛЮЧЕВЫХ ЗОН КОНТРОЛЯ В СИСТЕМЕ ГЕОТЕХНИЧЕСКОГО МОНИТОРИНГА

In this paper, we propose an algorithm for identifying key zones of geotechnical monitoring based on the data of an information and analytical system. The proposed algorithm is based on the analysis of the stability of individual sections of the geotechnical system, group stability using a neural network approach and a basic model. The training sample is formed on the basis of the geotechnical system model and a priori information. To isolate homogeneous reactions of a geotechnical system at different values of its parameters, the data clustering procedure is used. The correction of the permissible limits of the output of the controlled parameters is proposed to be carried out taking into account the results of the bifurcation analysis. The practical verification of the proposed algorithm was carried out on the monitoring data of a three–story building. The results obtained during the processing of the data of the information and analytical system of geotechnical monitoring by the proposed algorithm are consistent with the measurement and modeling data.

I-BIM based approach for geotechnical and numerical modelling of a conventional tunnel excavation

Very recently the Building Information Modeling (BIM) design approach has landed in the infrastructure field, giving life to the I-BIM, the BIM for the infrastructures, including geotechnical underground works likes tunnels. In this framework, the present paper shows an application in the field of geotechnical engineering of the BIM based design approach to the case of an underground line. It is a tunnel excavated by means of traditional method, currently under construction. The project defines, in a central BIM model, a detailed tunnel structure model integrated with geological-geotechnical information for the definition of the subsoil 3D model. Once the BIM model of the tunnel stretch under study was completely defined, it was imported into a finite element (FE) model to perform deformation analyses. Thus, BIM-to-FEM-to-BIM interoperability was exploited in order to verify the maturity level of the BIM approach in the field of application for geotechnical infrastructures. Finally, the BIM fourth dimension (4D) was also implemented in the central model for the time management of the tunnel excavation process, synchronized with the numerical model. The BIM based procedure proposed in the present work can be considered as a case study in the technical literature of I-BIM for tunnels, putting in evidence limitations and advantages: i) a high level of BIM maturity was not yet achieved in the infrastructures field; ii) the BIM-to-FEM interoperability seems to be not fully effective and many operations still require the manual intervention; iii) the FEM-to-BIM interoperability brings back all geotechnical choices and hypothesis to the central BIM model, linking the models into a continuously interoperable circuit; iv) an important part of the design of civil infrastructures consists of addressing geotechnical aspects, hence the inclusion of ground conditions and geotechnical data into the BIM model can improve the quality and the usefulness of the model, not only during the design phase but also, and in particular, during the construction and the lifecycle management of the infrastructure, as a support to decision making process especially in urban context.

Seismic response of a novel hybrid foundation for offshore wind turbine by geotechnical centrifuge modeling

Offshore wind farms are built in coastal areas prone to have earthquakes. When offshore wind turbines (OWTs) erected on cohesionless sediments are subjected to earthquakes, liquefaction might occur in the shallow deposits that might lead to severe overturning and settlement of the foundation structure. A novel hybrid foundation structure is proposed in this paper consisting of three major components: monopile, friction wheel, and suction bucket. This paper focuses on the performance of the hybrid foundation under earthquake loads. Hybrid foundation models with different dimensions were installed on both dry and saturated loose sand deposits and subjected to dynamic geotechnical centrifuge tests. Pore-water transducers were embedded in the soil to monitor its susceptibility to liquefaction. The dynamic responses of the superstructure were also monitored by linear variable differential transducers (LVDTs) and accelerometers. The experimental results indicated that the new hybrid foundation improved the ground liquefaction resistance. The extent of improvements was more significant in saturated sand than in dry sand. In saturated sand, it was observed that the hybrid foundation with larger bucket depth densified the surrounding soil and helped to mitigate the liquefaction. Consequently, the hybrid system showed responses of a stiffer foundation where the lateral displacement and settlement were reduced significantly.

A numerical geotechnical model for computing soil slides at banks of water reservoirs

Soil slides can occur when the water level in a lake or a reservoir is lowered. This may take place in situations when a reservoir is flushed to remove sediments. The current study describes a three-dimensional numerical model used for the simulation of reservoir flushing that includes the slide movements. The geotechnical failure algorithms start with modelling the groundwater levels at the banks of the reservoir. A limit equilibrium approach is further used to find the location of the slides. The actual movement of the sediments is computed by assuming the soil to be a viscous liquid and by solving the Navier–Stokes equations. The resulting bed elevation changes from the slides are computed in adaptive grids that change as a function of water level, bed erosion and slide movements. The numerical model is tested on the Bodendorf reservoir in Austria, where field measurements are available of the bank elevations before and after a flushing operation. The results from the numerical simulations are compared with these observations. A parameter test shows that the results are very sensitive to the cohesion and less sensitive to the E and G modules of the soil.

Geotechnical Analysis and 3D Fem Modeling of Ville San Pietro (Italy)

The paper describes the three-dimensional numerical model of Ville San Pietro, an Italian village subject to slope movements causing damage. The church (dating back to 1776), which is the most significant building of the area, is modelled too. The information from geotechnical and geophysical surveys on field are used to define the model geometry and the soil properties. A finite element code is adopted to simulate the slope behavior in occurrence of water table fluctuations, detected by piezometers, and to evaluate the slope displacements and stability. The validation of the model is carried out using the inclinometer and interferometry measures and by on-site inspections. The model demonstrated a good ability to simulate the slope behavior during the raising and lowering of the water table. The critical areas computed by the numerical code are in good accordance to the actual portions affected by soil displacements and damages. The modelling presented in this paper is crucial for future analyses that will take advantage of an innovative monitoring system, which will be installed on site.

Joint interpretation of electrical and seismic data aimed at modelling the foundation soils of the Maredolce monumental complex in Palermo (Italy)

AbstractThe monumental complex of Maredolce (Palermo) includes an Arab‐Norman castle that stands on the banks of an artificial lake carved out of the calcarenitic rock that rests on impermeable clays. The lake was originally filled with water, thanks to the channelling of a spring. Over time, the lowering of the water table and the high hydraulic permeability of the calcarenites have caused the lake to dry up. A project to renovate the monumental complex has recently been launched. It also provides the study of a possible restoration of the original conditions of the lake. To this end, a multidisciplinary geophysical study was carried out to investigate the geotechnical conditions of permeability of the land outcropping and provides valid technical solutions for waterproofing the bottom of the lake. For this purpose, a joint interpretation was performed using data acquired with different geophysical techniques, such as seismic refraction tomography, electrical resistivity and induced polarization tomography, multichannel analysis of surface waves and horizontal‐to‐vertical spectral ratio of environmental vibration recording. Joint interpretation, supported by cluster analysis techniques, allowed the reconstruction of the geophysical and geotechnical model of the subsoil of the ancient lake, helpful to suggest appropriate techniques for waterproofing the bottom of the lake.

Numerical Analysis of Geotechnical Problems of Historic Masonry Structures

Geotechnical modeling of complex soil problems requires an advanced 3D discretization and a sophisticated soil models. The aim of the present study is to accurately analysis the geotechnical and induced structural failure mechanisms observed in the field and experimental studies. In order to provide a contribution to quantify the stress and deformation analysis and settlement of soft clay subsoil, a geotechnical analytical model is presented in details. The study presents an attempt of a PLAXIS 3D FE analysis model to simulate the subsoil problems, deformation and stress analysis of the multi-layer masonry structures of Abu Serga church in Cairo, Egypt which is loaded in plane. Advanced soil plastic modeling has been used throughout the different phases of the numerical analysis. The numerical and experimental analysis allowed us to define the pathology of this unique architectural heritage and to estimate the subsoil deformation as well as the stress–strain analysis of its superstructure, also to define the ultimate load that they can survive under their present conditions. The results are discussed with respect to the stress–strain and volumetric behavior of the soil. Consequently it can be concluded that modeling the behavior of subsoil soft clay underneath Abu Serga church by the Numerical analysis is suitable for understanding of the studied behavior of this kind of problematic soil.

Numerical simulation of the seismic response and soil\u2013structure interaction for a monitored masonry school building damaged by the 2016 Central Italy earthquake

Despite significant research advances on the seismic response analysis, there is still an urgent need for validation of numerical simulation methods for prediction of earthquake response and damage. In this respect, seismic monitoring networks and proper modelling can further support validation studies, allowing more realistic simulations of what earthquakes can produce. This paper discusses the seismic response of the “Pietro Capuzi” school in Visso, a village located in the Marche region (Italy) that was severely damaged by the 2016–2017 Central Italy earthquake sequence. The school was a two-story masonry structure founded on simple enlargements of its load-bearing walls, partially embedded in the alluvial loose soils of the Nera river. The structure was monitored as a strategic building by the Italian Seismic Observatory of Structures (OSS), which provided acceleration records under both ambient noise and the three mainshocks of the seismic sequence. The evolution of the damage pattern following each one of the three mainshocks was provided by on-site survey integrated by OSS data. Data on the dynamic soil properties was available from the seismic microzonation study of the Visso village and proved useful in the development of a reliable geotechnical model of the subsoil. The equivalent frame (EF) approach was adopted to simulate the nonlinear response of the school building through both fixed-base and compliant-base models, to assess the likely influence of soil–structure interaction on the building performance. The ambient noise records allowed for an accurate calibration of the soil–structure model. The seismic response of the masonry building to the whole sequence of the three mainshocks was then simulated by nonlinear time history analyses by using the horizontal accelerations recorded at the underground floor as input motions. Numerical results are validated against the evidence on structural response in terms of both incremental damage and global shear force–displacement relationships. The comparisons are satisfactory, corroborating the reliability of the compliant-base approach as applied to the EF model and its computational efficiency to simulate the soil–foundation–structure interaction in the case of masonry buildings.

Assessing the earth dams’ effect on the groundwater of its location case study: Kord-Oliya dam

The main objective of the construction of the Kord-Oliya earth dam is to reserve surplus water for consumption and artificial recharge in the area. The effect of such dams on the basin is to alter the hydrological regime of its adjacent areas to somehow prevent drought. By considering the existence of such dams and the costs of their construction, operation, and maintenance, it is necessary to study their effect on surrounding groundwater. The objective of this study is to combine a geotechnical model for the subject earth dam through SEEP 3D software and its output in hydrogeological model through GMS software in a 3D mode for surface and groundwater management in a simultaneous manner. It is necessary to estimate the groundwater level of the area, to determine the hydrogeological and geotechnical conditions of the aquifer through mathematical models for optimal exploitation of the Karvan Plain. Excessive water harvesting for agriculture consumption from the Karvan aquifer has been and is on an increase which has led to a decrease in groundwater level in the area and introduced many environmental risks. This modeling is calibrated and validated for 121 months on this aquifer in both the steady and unsteady states in two scenarios with and without this earth dam. The obtained results indicate that existence of this dam does not increase the groundwater level in a gradual manner in the area in the consecutive years, while the mean groundwater level is on an increase by 14 m. By considering scenario one, the total volume of alluvial aquifer reserves increase 83.4 Mm3.