# Memory allocation, System freezes

**URL:** <https://forum.itascainternational.com/t/memory-allocation-system-freezes/744>\
**Category:** PFC\
**Created:** [September 8, 2022, 9:18am UTC](https://forum.itascainternational.com/t/memory-allocation-system-freezes/744 "2022-09-08T09:18:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Prerna](https://avatars.discourse-cdn.com/v4/letter/p/eada6e/32.png) [@Prerna](https://forum.itascainternational.com/u/Prerna)\
**Post date:** [September 8, 2022, 9:18am UTC](https://forum.itascainternational.com/t/memory-allocation-system-freezes/744/1 "2022-09-08T09:18:25Z")

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Dear Sir,  
I am attempting to simulate the retaining wall soil system. I am trying to validate a problem in PFC 3D and was considering the dimensions as per the paper. I have attached the paper and data file for reference.  
I am still working on the model, although it hangs as soon as I run line number 53.

For the foundation part, around 30,000 spherical balls were generated, and after that, when I applied the ‘model cycle 1000 calm 100’ command, the system hung, and  
then I had to shut down the system. The paper which I have attached also used PFC software.

Is it not possible to simulate such a large number of balls? Or is there a way to allocate memory to PFC so that my system does not hang?

Please help me out.  
[soil\_wall\_7\_9\_22.dat](https://forum.itascainternational.com/uploads/short-url/dT7bnsiCVmZniuwqox87F5qEjt.dat) (5.2 KB)  
[9780784482810.034.pdf](https://forum.itascainternational.com/uploads/short-url/9ag625VbNTkRgcdXs1UQDCPjzes.pdf) (719.3 KB)

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**Author:** ![Prerna](https://avatars.discourse-cdn.com/v4/letter/p/eada6e/32.png) [@Prerna](https://forum.itascainternational.com/u/Prerna)\
**Post date:** [September 12, 2022, 11:51am UTC](https://forum.itascainternational.com/t/memory-allocation-system-freezes/744/2 "2022-09-12T11:51:23Z")

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Hello.  
Can anyone help me out here?

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**Author:** ![dblanksma](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@dblanksma](https://forum.itascainternational.com/u/dblanksma)\
**Post date:** [September 12, 2022, 1:26pm UTC](https://forum.itascainternational.com/t/memory-allocation-system-freezes/744/3 "2022-09-12T13:26:04Z")

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Hello Prerna,

30k balls is certainly a reasonable number of balls to simulate quickly. I will take a look at your data file and see what may be the problem. Could you please let me know which version of _PFC_ you are using?

Thanks,  
Derrick

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**Author:** ![dblanksma](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@dblanksma](https://forum.itascainternational.com/u/dblanksma)\
**Post date:** [September 12, 2022, 8:42pm UTC](https://forum.itascainternational.com/t/memory-allocation-system-freezes/744/4 "2022-09-12T20:42:34Z")

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In any case, the problem resides in the `contact cmat proximity` command. You are giving the proximity a value that is 20x more than the largest radius of the balls. Therefore millions of contacts are being created between balls that are within a contact distance that you specified with this command.

I suggest reducing the contact proximity to a much smaller value.

– Derrick